Fix memory leak in `await new Response(latin1String).arrayBuffer()` and `await Response.json(obj).json()` (#3656)

❯ mem bun --smol response-arrayBuffer.mjs
cpu: Apple M1 Max
runtime: bun 0.6.15 (arm64-darwin)

benchmark                                                        time (avg)             (min … max)       p75       p99      p995
--------------------------------------------------------------------------------------------------- -----------------------------
new Response().arrayBuffer() (new string each call, latin1)    12.9 µs/iter      (625 ns … 4.18 ms)      1 µs 567.17 µs 711.79 µs
new Response().arrayBuffer() (new string each call, utf16)    12.85 µs/iter     (1.67 µs … 1.56 ms)   2.17 µs 462.75 µs 621.13 µs
new Response().arrayBuffer() (existing string, latin1)         6.53 µs/iter     (6.21 µs … 7.07 µs)   6.64 µs   7.07 µs   7.07 µs

Peak memory usage: 49 MB

bun on  jarred/memory-leak-fix took 2s
❯ mem bun response-arrayBuffer.mjs
cpu: Apple M1 Max
runtime: bun 0.6.15 (arm64-darwin)

benchmark                                                        time (avg)             (min … max)       p75       p99      p995
--------------------------------------------------------------------------------------------------- -----------------------------
new Response().arrayBuffer() (new string each call, latin1)     1.2 µs/iter     (1.04 µs … 1.42 µs)   1.22 µs   1.42 µs   1.42 µs
new Response().arrayBuffer() (new string each call, utf16)     2.74 µs/iter     (2.42 µs … 6.37 µs)   2.68 µs   6.37 µs   6.37 µs
new Response().arrayBuffer() (existing string, latin1)       746.37 ns/iter   (643.82 ns … 1.04 µs) 776.11 ns   1.04 µs   1.04 µs

Peak memory usage: 104 MB

bun on  jarred/memory-leak-fix took 2s
❯ mem ~/.bun/bin/bun response-arrayBuffer.mjs
cpu: Apple M1 Max
runtime: bun 0.6.15 (arm64-darwin)

benchmark                                                        time (avg)             (min … max)       p75       p99      p995
--------------------------------------------------------------------------------------------------- -----------------------------
new Response().arrayBuffer() (new string each call, latin1)    1.69 µs/iter      (1.56 µs … 2.1 µs)   1.73 µs    2.1 µs    2.1 µs
new Response().arrayBuffer() (new string each call, utf16)     2.65 µs/iter     (2.47 µs … 3.17 µs)   2.69 µs   3.17 µs   3.17 µs
new Response().arrayBuffer() (existing string, latin1)       667.67 ns/iter   (547.67 ns … 1.28 µs) 694.21 ns   1.28 µs   1.28 µs

Peak memory usage: 2735 MB

bun on  jarred/memory-leak-fix took 2s
❯ mem ~/.bun/bin/bun --smol response-arrayBuffer.mjs
cpu: Apple M1 Max
runtime: bun 0.6.15 (arm64-darwin)

benchmark                                                        time (avg)             (min … max)       p75       p99      p995
--------------------------------------------------------------------------------------------------- -----------------------------
new Response().arrayBuffer() (new string each call, latin1)   13.51 µs/iter       (541 ns … 3.2 ms)   1.92 µs 553.42 µs 709.92 µs
new Response().arrayBuffer() (new string each call, utf16)    13.07 µs/iter     (1.71 µs … 3.43 ms)   2.13 µs 451.21 µs 651.67 µs
new Response().arrayBuffer() (existing string, latin1)         6.25 µs/iter     (5.79 µs … 6.81 µs)    6.4 µs   6.81 µs   6.81 µs

Peak memory usage: 292 MB

Co-authored-by: Jarred Sumner <709451+Jarred-Sumner@users.noreply.github.com>

16 files changed, 361 insertions, 102 deletions

diff --git a/bench/snippets/response-arrayBuffer.mjs b/bench/snippets/response-arrayBuffer.mjs
new file mode 100644
index 000000000..a3b1f0a73
--- /dev/null
+++ b/bench/snippets/response-arrayBuffer.mjs
@@ -0,0 +1,136 @@
+// This snippet mostly exists to reproduce a memory leak
+//
+import { bench, run } from "mitata";
+
+const obj = {
+  "id": 1296269,
+  "node_id": "MDEwOlJlcG9zaXRvcnkxMjk2MjY5",
+  "name": "Hello-World",
+  "full_name": "octocat/Hello-World",
+  "owner": {
+    "login": "octocat",
+    "id": 1,
+    "node_id": "MDQ6VXNlcjE=",
+    "avatar_url": "https://github.com/images/error/octocat_happy.gif",
+    "gravatar_id": "",
+    "url": "https://api.github.com/users/octocat",
+    "html_url": "https://github.com/octocat",
+    "followers_url": "https://api.github.com/users/octocat/followers",
+    "following_url": "https://api.github.com/users/octocat/following{/other_user}",
+    "gists_url": "https://api.github.com/users/octocat/gists{/gist_id}",
+    "starred_url": "https://api.github.com/users/octocat/starred{/owner}{/repo}",
+    "subscriptions_url": "https://api.github.com/users/octocat/subscriptions",
+    "organizations_url": "https://api.github.com/users/octocat/orgs",
+    "repos_url": "https://api.github.com/users/octocat/repos",
+    "events_url": "https://api.github.com/users/octocat/events{/privacy}",
+    "received_events_url": "https://api.github.com/users/octocat/received_events",
+    "type": "User",
+    "site_admin": false,
+  },
+  "private": false,
+  "html_url": "https://github.com/octocat/Hello-World",
+  "description": "This your first repo!",
+  "fork": false,
+  "url": "https://api.github.com/repos/octocat/Hello-World",
+  "archive_url": "https://api.github.com/repos/octocat/Hello-World/{archive_format}{/ref}",
+  "assignees_url": "https://api.github.com/repos/octocat/Hello-World/assignees{/user}",
+  "blobs_url": "https://api.github.com/repos/octocat/Hello-World/git/blobs{/sha}",
+  "branches_url": "https://api.github.com/repos/octocat/Hello-World/branches{/branch}",
+  "collaborators_url": "https://api.github.com/repos/octocat/Hello-World/collaborators{/collaborator}",
+  "comments_url": "https://api.github.com/repos/octocat/Hello-World/comments{/number}",
+  "commits_url": "https://api.github.com/repos/octocat/Hello-World/commits{/sha}",
+  "compare_url": "https://api.github.com/repos/octocat/Hello-World/compare/{base}...{head}",
+  "contents_url": "https://api.github.com/repos/octocat/Hello-World/contents/{+path}",
+  "contributors_url": "https://api.github.com/repos/octocat/Hello-World/contributors",
+  "deployments_url": "https://api.github.com/repos/octocat/Hello-World/deployments",
+  "downloads_url": "https://api.github.com/repos/octocat/Hello-World/downloads",
+  "events_url": "https://api.github.com/repos/octocat/Hello-World/events",
+  "forks_url": "https://api.github.com/repos/octocat/Hello-World/forks",
+  "git_commits_url": "https://api.github.com/repos/octocat/Hello-World/git/commits{/sha}",
+  "git_refs_url": "https://api.github.com/repos/octocat/Hello-World/git/refs{/sha}",
+  "git_tags_url": "https://api.github.com/repos/octocat/Hello-World/git/tags{/sha}",
+  "git_url": "git:github.com/octocat/Hello-World.git",
+  "issue_comment_url": "https://api.github.com/repos/octocat/Hello-World/issues/comments{/number}",
+  "issue_events_url": "https://api.github.com/repos/octocat/Hello-World/issues/events{/number}",
+  "issues_url": "https://api.github.com/repos/octocat/Hello-World/issues{/number}",
+  "keys_url": "https://api.github.com/repos/octocat/Hello-World/keys{/key_id}",
+  "labels_url": "https://api.github.com/repos/octocat/Hello-World/labels{/name}",
+  "languages_url": "https://api.github.com/repos/octocat/Hello-World/languages",
+  "merges_url": "https://api.github.com/repos/octocat/Hello-World/merges",
+  "milestones_url": "https://api.github.com/repos/octocat/Hello-World/milestones{/number}",
+  "notifications_url": "https://api.github.com/repos/octocat/Hello-World/notifications{?since,all,participating}",
+  "pulls_url": "https://api.github.com/repos/octocat/Hello-World/pulls{/number}",
+  "releases_url": "https://api.github.com/repos/octocat/Hello-World/releases{/id}",
+  "ssh_url": "git@github.com:octocat/Hello-World.git",
+  "stargazers_url": "https://api.github.com/repos/octocat/Hello-World/stargazers",
+  "statuses_url": "https://api.github.com/repos/octocat/Hello-World/statuses/{sha}",
+  "subscribers_url": "https://api.github.com/repos/octocat/Hello-World/subscribers",
+  "subscription_url": "https://api.github.com/repos/octocat/Hello-World/subscription",
+  "tags_url": "https://api.github.com/repos/octocat/Hello-World/tags",
+  "teams_url": "https://api.github.com/repos/octocat/Hello-World/teams",
+  "trees_url": "https://api.github.com/repos/octocat/Hello-World/git/trees{/sha}",
+  "clone_url": "https://github.com/octocat/Hello-World.git",
+  "mirror_url": "git:git.example.com/octocat/Hello-World",
+  "hooks_url": "https://api.github.com/repos/octocat/Hello-World/hooks",
+  "svn_url": "https://svn.github.com/octocat/Hello-World",
+  "homepage": "https://github.com",
+  "language": null,
+  "forks_count": 9,
+  "stargazers_count": 80,
+  "watchers_count": 80,
+  "size": 108,
+  "default_branch": "master",
+  "open_issues_count": 0,
+  "is_template": false,
+  "topics": ["octocat", "atom", "electron", "api"],
+  "has_issues": true,
+  "has_projects": true,
+  "has_wiki": true,
+  "has_pages": false,
+  "has_downloads": true,
+  "has_discussions": false,
+  "archived": false,
+  "disabled": false,
+  "visibility": "public",
+  "pushed_at": "2011-01-26T19:06:43Z",
+  "created_at": "2011-01-26T19:01:12Z",
+  "updated_at": "2011-01-26T19:14:43Z",
+  "permissions": {
+    "admin": false,
+    "push": false,
+    "pull": true,
+  },
+  "security_and_analysis": {
+    "advanced_security": {
+      "status": "enabled",
+    },
+    "secret_scanning": {
+      "status": "enabled",
+    },
+    "secret_scanning_push_protection": {
+      "status": "disabled",
+    },
+  },
+};
+
+// Force the string to be 8bit
+const str = String.fromCharCode(
+  ...JSON.stringify(obj)
+    .split("")
+    .map(a => a.charCodeAt(0)),
+);
+var i = 0;
+
+bench("new Response().arrayBuffer() (new string each call, latin1)", async () => {
+  return await new Response(str + i++).arrayBuffer();
+});
+
+bench("new Response().arrayBuffer() (new string each call, utf16)", async () => {
+  return await new Response(str + i++ + "😊").arrayBuffer();
+});
+
+bench("new Response().arrayBuffer() (existing string, latin1)", async () => {
+  return await new Response(str).arrayBuffer();
+});
+
+await run();
diff --git a/bench/snippets/response-json.mjs b/bench/snippets/response-json.mjs
new file mode 100644
index 000000000..dd28203f0
--- /dev/null
+++ b/bench/snippets/response-json.mjs
@@ -0,0 +1,123 @@
+// This snippet mostly exists to reproduce a memory leak
+import { bench, run } from "mitata";
+
+const obj = {
+  "id": 1296269,
+  "node_id": "MDEwOlJlcG9zaXRvcnkxMjk2MjY5",
+  "name": "Hello-World",
+  "full_name": "octocat/Hello-World",
+  "owner": {
+    "login": "octocat",
+    "id": 1,
+    "node_id": "MDQ6VXNlcjE=",
+    "avatar_url": "https://github.com/images/error/octocat_happy.gif",
+    "gravatar_id": "",
+    "url": "https://api.github.com/users/octocat",
+    "html_url": "https://github.com/octocat",
+    "followers_url": "https://api.github.com/users/octocat/followers",
+    "following_url": "https://api.github.com/users/octocat/following{/other_user}",
+    "gists_url": "https://api.github.com/users/octocat/gists{/gist_id}",
+    "starred_url": "https://api.github.com/users/octocat/starred{/owner}{/repo}",
+    "subscriptions_url": "https://api.github.com/users/octocat/subscriptions",
+    "organizations_url": "https://api.github.com/users/octocat/orgs",
+    "repos_url": "https://api.github.com/users/octocat/repos",
+    "events_url": "https://api.github.com/users/octocat/events{/privacy}",
+    "received_events_url": "https://api.github.com/users/octocat/received_events",
+    "type": "User",
+    "site_admin": false,
+  },
+  "private": false,
+  "html_url": "https://github.com/octocat/Hello-World",
+  "description": "This your first repo!",
+  "fork": false,
+  "url": "https://api.github.com/repos/octocat/Hello-World",
+  "archive_url": "https://api.github.com/repos/octocat/Hello-World/{archive_format}{/ref}",
+  "assignees_url": "https://api.github.com/repos/octocat/Hello-World/assignees{/user}",
+  "blobs_url": "https://api.github.com/repos/octocat/Hello-World/git/blobs{/sha}",
+  "branches_url": "https://api.github.com/repos/octocat/Hello-World/branches{/branch}",
+  "collaborators_url": "https://api.github.com/repos/octocat/Hello-World/collaborators{/collaborator}",
+  "comments_url": "https://api.github.com/repos/octocat/Hello-World/comments{/number}",
+  "commits_url": "https://api.github.com/repos/octocat/Hello-World/commits{/sha}",
+  "compare_url": "https://api.github.com/repos/octocat/Hello-World/compare/{base}...{head}",
+  "contents_url": "https://api.github.com/repos/octocat/Hello-World/contents/{+path}",
+  "contributors_url": "https://api.github.com/repos/octocat/Hello-World/contributors",
+  "deployments_url": "https://api.github.com/repos/octocat/Hello-World/deployments",
+  "downloads_url": "https://api.github.com/repos/octocat/Hello-World/downloads",
+  "events_url": "https://api.github.com/repos/octocat/Hello-World/events",
+  "forks_url": "https://api.github.com/repos/octocat/Hello-World/forks",
+  "git_commits_url": "https://api.github.com/repos/octocat/Hello-World/git/commits{/sha}",
+  "git_refs_url": "https://api.github.com/repos/octocat/Hello-World/git/refs{/sha}",
+  "git_tags_url": "https://api.github.com/repos/octocat/Hello-World/git/tags{/sha}",
+  "git_url": "git:github.com/octocat/Hello-World.git",
+  "issue_comment_url": "https://api.github.com/repos/octocat/Hello-World/issues/comments{/number}",
+  "issue_events_url": "https://api.github.com/repos/octocat/Hello-World/issues/events{/number}",
+  "issues_url": "https://api.github.com/repos/octocat/Hello-World/issues{/number}",
+  "keys_url": "https://api.github.com/repos/octocat/Hello-World/keys{/key_id}",
+  "labels_url": "https://api.github.com/repos/octocat/Hello-World/labels{/name}",
+  "languages_url": "https://api.github.com/repos/octocat/Hello-World/languages",
+  "merges_url": "https://api.github.com/repos/octocat/Hello-World/merges",
+  "milestones_url": "https://api.github.com/repos/octocat/Hello-World/milestones{/number}",
+  "notifications_url": "https://api.github.com/repos/octocat/Hello-World/notifications{?since,all,participating}",
+  "pulls_url": "https://api.github.com/repos/octocat/Hello-World/pulls{/number}",
+  "releases_url": "https://api.github.com/repos/octocat/Hello-World/releases{/id}",
+  "ssh_url": "git@github.com:octocat/Hello-World.git",
+  "stargazers_url": "https://api.github.com/repos/octocat/Hello-World/stargazers",
+  "statuses_url": "https://api.github.com/repos/octocat/Hello-World/statuses/{sha}",
+  "subscribers_url": "https://api.github.com/repos/octocat/Hello-World/subscribers",
+  "subscription_url": "https://api.github.com/repos/octocat/Hello-World/subscription",
+  "tags_url": "https://api.github.com/repos/octocat/Hello-World/tags",
+  "teams_url": "https://api.github.com/repos/octocat/Hello-World/teams",
+  "trees_url": "https://api.github.com/repos/octocat/Hello-World/git/trees{/sha}",
+  "clone_url": "https://github.com/octocat/Hello-World.git",
+  "mirror_url": "git:git.example.com/octocat/Hello-World",
+  "hooks_url": "https://api.github.com/repos/octocat/Hello-World/hooks",
+  "svn_url": "https://svn.github.com/octocat/Hello-World",
+  "homepage": "https://github.com",
+  "language": null,
+  "forks_count": 9,
+  "stargazers_count": 80,
+  "watchers_count": 80,
+  "size": 108,
+  "default_branch": "master",
+  "open_issues_count": 0,
+  "is_template": false,
+  "topics": ["octocat", "atom", "electron", "api"],
+  "has_issues": true,
+  "has_projects": true,
+  "has_wiki": true,
+  "has_pages": false,
+  "has_downloads": true,
+  "has_discussions": false,
+  "archived": false,
+  "disabled": false,
+  "visibility": "public",
+  "pushed_at": "2011-01-26T19:06:43Z",
+  "created_at": "2011-01-26T19:01:12Z",
+  "updated_at": "2011-01-26T19:14:43Z",
+  "permissions": {
+    "admin": false,
+    "push": false,
+    "pull": true,
+  },
+  "security_and_analysis": {
+    "advanced_security": {
+      "status": "enabled",
+    },
+    "secret_scanning": {
+      "status": "enabled",
+    },
+    "secret_scanning_push_protection": {
+      "status": "disabled",
+    },
+  },
+};
+
+bench("Response.json(obj)", async () => {
+  return Response.json(obj);
+});
+
+bench("Response.json(obj).json()", async () => {
+  return await Response.json(obj).json();
+});
+
+await run();
diff --git a/src/bun.js/api/JSTranspiler.zig b/src/bun.js/api/JSTranspiler.zig
index 308738abf..95b0eeaae 100644
--- a/src/bun.js/api/JSTranspiler.zig
+++ b/src/bun.js/api/JSTranspiler.zig
@@ -442,7 +442,8 @@ fn transformOptionsFromJSC(globalObject: JSC.C.JSContextRef, temp_allocator: std
         tsconfig: {
             if (tsconfig.isUndefinedOrNull()) break :tsconfig;
             const kind = tsconfig.jsType();
-            var out = JSC.ZigString.init("");
+            var out = bun.String.empty;
+            defer out.deref();
 
             if (kind.isArray()) {
                 JSC.throwInvalidArguments("tsconfig must be a string or object", .{}, globalObject, exception);
@@ -452,11 +453,11 @@ fn transformOptionsFromJSC(globalObject: JSC.C.JSContextRef, temp_allocator: std
             if (!kind.isStringLike()) {
                 tsconfig.jsonStringify(globalThis, 0, &out);
             } else {
-                tsconfig.toZigString(&out, globalThis);
+                out = tsconfig.toBunString(globalThis);
             }
 
-            if (out.len == 0) break :tsconfig;
-            transpiler.tsconfig_buf = std.fmt.allocPrint(allocator, "{}", .{out}) catch unreachable;
+            if (out.isEmpty()) break :tsconfig;
+            transpiler.tsconfig_buf = out.toOwnedSlice(allocator) catch @panic("OOM");
 
             // TODO: JSC -> Ast conversion
             if (TSConfigJSON.parse(
@@ -490,16 +491,17 @@ fn transformOptionsFromJSC(globalObject: JSC.C.JSContextRef, temp_allocator: std
                 return transpiler;
             }
 
-            var out: ZigString = ZigString.init("");
+            var out = bun.String.empty;
+            defer out.deref();
             // TODO: write a converter between JSC types and Bun AST types
             if (is_object) {
                 macros.jsonStringify(globalThis, 0, &out);
             } else {
-                macros.toZigString(&out, globalThis);
+                out = macros.toBunString(globalThis);
             }
 
-            if (out.len == 0) break :macros;
-            transpiler.macros_buf = std.fmt.allocPrint(allocator, "{}", .{out}) catch unreachable;
+            if (out.isEmpty()) break :macros;
+            transpiler.macros_buf = out.toOwnedSlice(allocator) catch @panic("OOM");
             const source = logger.Source.initPathString("macros.json", transpiler.macros_buf);
             const json = (VirtualMachine.get().bundler.resolver.caches.json.parseJSON(
                 &transpiler.log,
diff --git a/src/bun.js/base.zig b/src/bun.js/base.zig
index 4a1249b5d..535c08395 100644
--- a/src/bun.js/base.zig
+++ b/src/bun.js/base.zig
@@ -1854,6 +1854,8 @@ pub const ArrayBuffer = extern struct {
         ));
     }
 
+    const log = Output.scoped(.ArrayBuffer, false);
+
     pub fn toJS(this: ArrayBuffer, ctx: JSC.C.JSContextRef, exception: JSC.C.ExceptionRef) JSC.JSValue {
         if (!this.value.isEmpty()) {
             return this.value;
@@ -1861,6 +1863,8 @@ pub const ArrayBuffer = extern struct {
 
         // If it's not a mimalloc heap buffer, we're not going to call a deallocator
         if (this.len > 0 and !bun.Mimalloc.mi_is_in_heap_region(this.ptr)) {
+            log("toJS but will never free: {d} bytes", .{this.len});
+
             if (this.typed_array_type == .ArrayBuffer) {
                 return JSC.JSValue.fromRef(JSC.C.JSObjectMakeArrayBufferWithBytesNoCopy(
                     ctx,
diff --git a/src/bun.js/bindings/BunString.cpp b/src/bun.js/bindings/BunString.cpp
index 21541d711..0676dce19 100644
--- a/src/bun.js/bindings/BunString.cpp
+++ b/src/bun.js/bindings/BunString.cpp
@@ -5,6 +5,8 @@
 #include "simdutf.h"
 #include "wtf/text/ExternalStringImpl.h"
 #include "GCDefferalContext.h"
+#include <JavaScriptCore/JSONObject.h>
+
 using namespace JSC;
 
 extern "C" bool Bun__WTFStringImpl__hasPrefix(const WTF::StringImpl* impl, const char* bytes, size_t length)
@@ -231,6 +233,19 @@ extern "C" BunString BunString__createExternal(const char* bytes, size_t length,
     return { BunStringTag::WTFStringImpl, { .wtf = &impl.leakRef() } };
 }
 
+extern "C" EncodedJSValue BunString__toJSON(
+    JSC::JSGlobalObject* globalObject,
+    BunString* bunString)
+{
+    JSC::JSValue result = JSC::JSONParse(globalObject, Bun::toWTFString(*bunString));
+
+    if (!result) {
+        result = JSC::JSValue(JSC::createSyntaxError(globalObject, "Failed to parse JSON"_s));
+    }
+
+    return JSC::JSValue::encode(result);
+}
+
 extern "C" EncodedJSValue BunString__createArray(
     JSC::JSGlobalObject* globalObject,
     const BunString* ptr, size_t length)
diff --git a/src/bun.js/bindings/ZigGlobalObject.cpp b/src/bun.js/bindings/ZigGlobalObject.cpp
index 7c0e1668b..a5c96ee08 100644
--- a/src/bun.js/bindings/ZigGlobalObject.cpp
+++ b/src/bun.js/bindings/ZigGlobalObject.cpp
@@ -249,76 +249,6 @@ extern "C" void JSCInitialize(const char* envp[], size_t envc, void (*onCrash)(c
 #endif
         JSC::Options::useSetMethods() = true;
 
-        /*
-         * The Magic "Use Less RAM" button
-         */
-        // # With /= 16,184
-        // cpu: Apple M1 Max
-        // runtime: bun 0.6.10 (arm64-darwin)
-        // benchmark                        time (avg)             (min … max)       p75       p99      p995
-        // ------------------------------------------------------------------- -----------------------------
-        // crypto.createHash("sha512")  953.74 ns/iter   (842.34 ns … 1.11 µs)      1 µs   1.11 µs   1.11 µs
-        // crypto.createHash("sha256")  704.35 ns/iter  (594.42 ns … 912.4 ns) 754.89 ns  912.4 ns  912.4 ns
-        // crypto.createHash("sha1")    608.53 ns/iter (488.66 ns … 724.54 ns) 637.75 ns 724.54 ns 724.54 ns
-        // Peak memory usage: 59 MB
-        // # With /= 8096
-        // cpu: Apple M1 Max
-        // runtime: bun 0.6.10 (arm64-darwin)
-        // benchmark                        time (avg)             (min … max)       p75       p99      p995
-        // ------------------------------------------------------------------- -----------------------------
-        // crypto.createHash("sha512")  821.71 ns/iter   (716.88 ns … 1.01 µs) 859.07 ns   1.01 µs   1.01 µs
-        // crypto.createHash("sha256")  534.89 ns/iter (439.35 ns … 737.17 ns) 576.15 ns  633.4 ns 737.17 ns
-        // crypto.createHash("sha1")     529.1 ns/iter (432.46 ns … 766.94 ns) 566.07 ns 653.13 ns 766.94 ns
-        // Peak memory usage: 60 MB
-        // # With /= 1024
-        // cpu: Apple M1 Max
-        // runtime: bun 0.6.10 (arm64-darwin)
-        // benchmark                        time (avg)             (min … max)       p75       p99      p995
-        // ------------------------------------------------------------------- -----------------------------
-        // crypto.createHash("sha512")  751.13 ns/iter (703.45 ns … 947.73 ns) 754.54 ns 947.73 ns 947.73 ns
-        // crypto.createHash("sha256")  501.47 ns/iter (467.19 ns … 580.84 ns) 505.66 ns 572.42 ns 580.84 ns
-        // crypto.createHash("sha1")    482.16 ns/iter  (452.7 ns … 570.29 ns) 482.74 ns 565.52 ns 570.29 ns
-        // Peak memory usage: 169 MB
-        // # With /= 256
-        // cpu: Apple M1 Max
-        // runtime: bun 0.6.10 (arm64-darwin)
-        // benchmark                        time (avg)             (min … max)       p75       p99      p995
-        // ------------------------------------------------------------------- -----------------------------
-        // crypto.createHash("sha512")  745.25 ns/iter (705.91 ns … 863.73 ns)  747.8 ns 863.73 ns 863.73 ns
-        // crypto.createHash("sha256")  506.94 ns/iter (459.27 ns … 692.93 ns) 514.95 ns 611.72 ns 692.93 ns
-        // crypto.createHash("sha1")    486.19 ns/iter (456.13 ns … 749.72 ns)  487.5 ns 578.84 ns 749.72 ns
-        // Peak memory usage: 270 MB
-        // # Unset
-        // cpu: Apple M1 Max
-        // runtime: bun 0.6.10 (arm64-darwin)
-        // benchmark                        time (avg)             (min … max)       p75       p99      p995
-        // ------------------------------------------------------------------- -----------------------------
-        // crypto.createHash("sha512")  752.96 ns/iter (705.88 ns … 954.63 ns) 758.78 ns 954.63 ns 954.63 ns
-        // crypto.createHash("sha256")  503.72 ns/iter  (466.7 ns … 602.83 ns) 507.22 ns 593.72 ns 602.83 ns
-        // crypto.createHash("sha1")    484.25 ns/iter (454.55 ns … 555.84 ns) 487.96 ns 553.41 ns 555.84 ns
-        // Peak memory usage: 273 MB
-        // # Node.js, for comparison
-        // cpu: Apple M1 Max
-        // runtime: node v20.1.0 (arm64-darwin)
-        // benchmark                        time (avg)             (min … max)       p75       p99      p995
-        // ------------------------------------------------------------------- -----------------------------
-        // crypto.createHash("sha512")    1.82 µs/iter     (1.77 µs … 2.17 µs)   1.84 µs   2.17 µs   2.17 µs
-        // crypto.createHash("sha256")     964 ns/iter    (946.02 ns … 1.1 µs) 962.95 ns    1.1 µs    1.1 µs
-        // crypto.createHash("sha1")    985.26 ns/iter    (956.7 ns … 1.12 µs)      1 µs   1.12 µs   1.12 µs
-        // Peak memory usage: 56 MB
-        size_t ramSize = WTF::ramSize();
-
-        // We originally went with a hardcoded /= 1024 here
-        // But if you don't have much memory, that becomes a problem.
-        // Instead, we do 65%
-        double ramSizeDouble = static_cast<double>(ramSize);
-        ramSizeDouble *= 0.65;
-        ramSize = static_cast<size_t>(ramSizeDouble);
-
-        if (ramSize > 0) {
-            JSC::Options::forceRAMSize() = ramSize;
-        }
-
         if (LIKELY(envc > 0)) {
             while (envc--) {
                 const char* env = (const char*)envp[envc];
diff --git a/src/bun.js/bindings/bindings.cpp b/src/bun.js/bindings/bindings.cpp
index d311072e4..552da4009 100644
--- a/src/bun.js/bindings/bindings.cpp
+++ b/src/bun.js/bindings/bindings.cpp
@@ -1542,11 +1542,11 @@ void JSC__JSFunction__optimizeSoon(JSC__JSValue JSValue0)
 }
 
 void JSC__JSValue__jsonStringify(JSC__JSValue JSValue0, JSC__JSGlobalObject* arg1, uint32_t arg2,
-    ZigString* arg3)
+    BunString* arg3)
 {
     JSC::JSValue value = JSC::JSValue::decode(JSValue0);
     WTF::String str = JSC::JSONStringify(arg1, value, (unsigned)arg2);
-    *arg3 = Zig::toZigString(str);
+    *arg3 = Bun::toStringRef(str);
 }
 unsigned char JSC__JSValue__jsType(JSC__JSValue JSValue0)
 {
diff --git a/src/bun.js/bindings/bindings.zig b/src/bun.js/bindings/bindings.zig
index 7e3fa6d8e..a28bb4297 100644
--- a/src/bun.js/bindings/bindings.zig
+++ b/src/bun.js/bindings/bindings.zig
@@ -4164,7 +4164,7 @@ pub const JSValue = enum(JSValueReprInt) {
         return cppFn("toString", .{ this, globalThis });
     }
 
-    pub fn jsonStringify(this: JSValue, globalThis: *JSGlobalObject, indent: u32, out: *ZigString) void {
+    pub fn jsonStringify(this: JSValue, globalThis: *JSGlobalObject, indent: u32, out: *bun.String) void {
         return cppFn("jsonStringify", .{ this, globalThis, indent, out });
     }
 
diff --git a/src/bun.js/bindings/exports.zig b/src/bun.js/bindings/exports.zig
index 958a7ff20..8fed85c4a 100644
--- a/src/bun.js/bindings/exports.zig
+++ b/src/bun.js/bindings/exports.zig
@@ -2463,9 +2463,11 @@ pub const ZigConsoleClient = struct {
                     writer.writeAll("{}");
                 },
                 .JSON => {
-                    var str = ZigString.init("");
+                    var str = bun.String.empty;
+                    defer str.deref();
+
                     value.jsonStringify(this.globalThis, this.indent, &str);
-                    this.addForNewLine(str.len);
+                    this.addForNewLine(str.length());
                     if (jsType == JSValue.JSType.JSDate) {
                         // in the code for printing dates, it never exceeds this amount
                         var iso_string_buf: [36]u8 = undefined;
diff --git a/src/bun.js/bindings/headers.h b/src/bun.js/bindings/headers.h
index 8a03d5233..206a7e27c 100644
--- a/src/bun.js/bindings/headers.h
+++ b/src/bun.js/bindings/headers.h
@@ -377,7 +377,7 @@ CPP_DECL JSC__JSValue JSC__JSValue__jsNumberFromChar(unsigned char arg0);
 CPP_DECL JSC__JSValue JSC__JSValue__jsNumberFromDouble(double arg0);
 CPP_DECL JSC__JSValue JSC__JSValue__jsNumberFromInt64(int64_t arg0);
 CPP_DECL JSC__JSValue JSC__JSValue__jsNumberFromU16(uint16_t arg0);
-CPP_DECL void JSC__JSValue__jsonStringify(JSC__JSValue JSValue0, JSC__JSGlobalObject* arg1, uint32_t arg2, ZigString* arg3);
+CPP_DECL void JSC__JSValue__jsonStringify(JSC__JSValue JSValue0, JSC__JSGlobalObject* arg1, uint32_t arg2, BunString* arg3);
 CPP_DECL JSC__JSValue JSC__JSValue__jsTDZValue();
 CPP_DECL unsigned char JSC__JSValue__jsType(JSC__JSValue JSValue0);
 CPP_DECL JSC__JSValue JSC__JSValue__jsUndefined();
diff --git a/src/bun.js/bindings/headers.zig b/src/bun.js/bindings/headers.zig
index 343939cc2..155b7cce4 100644
--- a/src/bun.js/bindings/headers.zig
+++ b/src/bun.js/bindings/headers.zig
@@ -277,7 +277,7 @@ pub extern fn JSC__JSValue__jsNumberFromChar(arg0: u8) JSC__JSValue;
 pub extern fn JSC__JSValue__jsNumberFromDouble(arg0: f64) JSC__JSValue;
 pub extern fn JSC__JSValue__jsNumberFromInt64(arg0: i64) JSC__JSValue;
 pub extern fn JSC__JSValue__jsNumberFromU16(arg0: u16) JSC__JSValue;
-pub extern fn JSC__JSValue__jsonStringify(JSValue0: JSC__JSValue, arg1: *bindings.JSGlobalObject, arg2: u32, arg3: [*c]ZigString) void;
+pub extern fn JSC__JSValue__jsonStringify(JSValue0: JSC__JSValue, arg1: *bindings.JSGlobalObject, arg2: u32, arg3: [*c]BunString) void;
 pub extern fn JSC__JSValue__jsTDZValue(...) JSC__JSValue;
 pub extern fn JSC__JSValue__jsType(JSValue0: JSC__JSValue) u8;
 pub extern fn JSC__JSValue__jsUndefined(...) JSC__JSValue;
diff --git a/src/bun.js/javascript.zig b/src/bun.js/javascript.zig
index cfa791d63..2e6d61952 100644
--- a/src/bun.js/javascript.zig
+++ b/src/bun.js/javascript.zig
@@ -2431,9 +2431,10 @@ pub const VirtualMachine = struct {
                                 add_extra_line = true;
                             }
                         } else if (kind.isObject() or kind.isArray()) {
-                            var zig_str = ZigString.init("");
-                            value.jsonStringify(this.global, 2, &zig_str);
-                            try writer.print(comptime Output.prettyFmt(" {s}<d>: <r>{s}<r>\n", allow_ansi_color), .{ field, zig_str });
+                            var bun_str = bun.String.empty;
+                            defer bun_str.deref();
+                            value.jsonStringify(this.global, 2, &bun_str);
+                            try writer.print(comptime Output.prettyFmt(" {s}<d>: <r>{any}<r>\n", allow_ansi_color), .{ field, bun_str });
                             add_extra_line = true;
                         }
                     }
diff --git a/src/bun.js/test/pretty_format.zig b/src/bun.js/test/pretty_format.zig
index a6c6aa631..e907dd711 100644
--- a/src/bun.js/test/pretty_format.zig
+++ b/src/bun.js/test/pretty_format.zig
@@ -1403,9 +1403,11 @@ pub const JestPrettyFormat = struct {
                     writer.writeAll("\n");
                 },
                 .JSON => {
-                    var str = ZigString.init("");
+                    var str = bun.String.empty;
+                    defer str.deref();
+
                     value.jsonStringify(this.globalThis, this.indent, &str);
-                    this.addForNewLine(str.len);
+                    this.addForNewLine(str.length());
                     if (jsType == JSValue.JSType.JSDate) {
                         // in the code for printing dates, it never exceeds this amount
                         var iso_string_buf: [36]u8 = undefined;
diff --git a/src/bun.js/webcore/blob.zig b/src/bun.js/webcore/blob.zig
index 0d6dcbc26..7e0b7f24b 100644
--- a/src/bun.js/webcore/blob.zig
+++ b/src/bun.js/webcore/blob.zig
@@ -3798,7 +3798,7 @@ pub const AnyBlob = union(enum) {
                     return JSValue.jsNull();
                 }
 
-                return str.toJS(global).parseJSON(global);
+                return str.toJSForParseJSON(global);
             },
         }
     }
@@ -3867,7 +3867,7 @@ pub const AnyBlob = union(enum) {
                 this.* = .{ .Blob = .{} };
                 defer str.deref();
 
-                const out_bytes = str.toUTF8(bun.default_allocator);
+                const out_bytes = str.toUTF8WithoutRef(bun.default_allocator);
                 if (out_bytes.isAllocated()) {
                     const value = JSC.ArrayBuffer.fromBytes(
                         @constCast(out_bytes.slice()),
diff --git a/src/bun.js/webcore/response.zig b/src/bun.js/webcore/response.zig
index e888ffa5a..f27e7f9aa 100644
--- a/src/bun.js/webcore/response.zig
+++ b/src/bun.js/webcore/response.zig
@@ -387,22 +387,23 @@ pub const Response = struct {
         const json_value = args.nextEat() orelse JSC.JSValue.zero;
 
         if (@intFromEnum(json_value) != 0) {
-            var zig_str = JSC.ZigString.init("");
+            var str = bun.String.empty;
             // calling JSON.stringify on an empty string adds extra quotes
             // so this is correct
-            json_value.jsonStringify(globalThis.ptr(), 0, &zig_str);
+            json_value.jsonStringify(globalThis, 0, &str);
 
-            if (zig_str.len > 0) {
-                const allocator = getAllocator(globalThis);
-                var zig_str_slice = zig_str.toSlice(allocator);
-
-                if (zig_str_slice.isAllocated()) {
+            if (!str.isEmpty()) {
+                if (str.value.WTFStringImpl.toUTF8IfNeeded(bun.default_allocator)) |bytes| {
+                    defer str.deref();
                     response.body.value = .{
-                        .Blob = Blob.initWithAllASCII(zig_str_slice.mut(), allocator, globalThis.ptr(), false),
+                        .InternalBlob = InternalBlob{
+                            .bytes = std.ArrayList(u8).fromOwnedSlice(bun.default_allocator, @constCast(bytes.slice())),
+                            .was_string = true,
+                        },
                     };
                 } else {
-                    response.body.value = .{
-                        .Blob = Blob.initWithAllASCII(allocator.dupe(u8, zig_str_slice.slice()) catch unreachable, allocator, globalThis.ptr(), true),
+                    response.body.value = Body.Value{
+                        .WTFStringImpl = str.value.WTFStringImpl,
                     };
                 }
             }
diff --git a/src/string.zig b/src/string.zig
index 5f107197f..26cd86d8c 100644
--- a/src/string.zig
+++ b/src/string.zig
@@ -128,6 +128,22 @@ pub const WTFStringImplStruct = extern struct {
         return .{};
     }
 
+    pub fn toUTF8WithoutRef(this: WTFStringImpl, allocator: std.mem.Allocator) ZigString.Slice {
+        if (this.is8Bit()) {
+            if (bun.strings.toUTF8FromLatin1(allocator, this.latin1Slice()) catch null) |utf8| {
+                return ZigString.Slice.init(allocator, utf8.items);
+            }
+
+            return ZigString.Slice.fromUTF8NeverFree(this.latin1Slice());
+        }
+
+        if (bun.strings.toUTF8Alloc(allocator, this.utf16Slice()) catch null) |utf8| {
+            return ZigString.Slice.init(allocator, utf8);
+        }
+
+        return .{};
+    }
+
     pub fn toUTF8IfNeeded(this: WTFStringImpl, allocator: std.mem.Allocator) ?ZigString.Slice {
         if (this.is8Bit()) {
             if (bun.strings.toUTF8FromLatin1(allocator, this.latin1Slice()) catch null) |utf8| {
@@ -533,6 +549,16 @@ pub const String = extern struct {
         return false;
     }
 
+    extern fn BunString__toJSON(
+        globalObject: *bun.JSC.JSGlobalObject,
+        this: *String,
+    ) JSC.JSValue;
+
+    pub fn toJSForParseJSON(self: *String, globalObject: *JSC.JSGlobalObject) JSC.JSValue {
+        JSC.markBinding(@src());
+        return BunString__toJSON(globalObject, self);
+    }
+
     pub fn encodeInto(self: String, out: []u8, comptime enc: JSC.Node.Encoding) !usize {
         if (self.isUTF16()) {
             return JSC.WebCore.Encoder.encodeIntoFrom16(self.utf16(), out, enc, true);
@@ -581,6 +607,23 @@ pub const String = extern struct {
         return ZigString.Slice.empty;
     }
 
+    /// This is the same as toUTF8, but it doesn't increment the reference count for latin1 strings
+    pub fn toUTF8WithoutRef(this: String, allocator: std.mem.Allocator) ZigString.Slice {
+        if (this.tag == .WTFStringImpl) {
+            return this.value.WTFStringImpl.toUTF8WithoutRef(allocator);
+        }
+
+        if (this.tag == .ZigString) {
+            return this.value.ZigString.toSlice(allocator);
+        }
+
+        if (this.tag == .StaticZigString) {
+            return ZigString.Slice.fromUTF8NeverFree(this.value.StaticZigString.slice());
+        }
+
+        return ZigString.Slice.empty;
+    }
+
     pub fn toSlice(this: String, allocator: std.mem.Allocator) SliceWithUnderlyingString {
         return SliceWithUnderlyingString{
             .utf8 = this.toUTF8(allocator),