3 files changed, 57 insertions, 2 deletions
diff --git a/.prettierignore b/.prettierignore
index ebb14dfbd..d5f16029d 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -1,9 +1,8 @@
 src/fallback.html
 # src/test
-bench
 test/bun.js/solid-dom-fixtures
 test/bun.js/bundled
 src/bun.js/builtins
 # src/api/demo
 test/snapshots
-test/snapshots-no-hmr
-\ No newline at end of file
+test/snapshots-no-hmr
diff --git a/bench/snippets/headers.mjs b/bench/snippets/headers.mjs
new file mode 100644
index 000000000..ace0d9f00
--- /dev/null
+++ b/bench/snippets/headers.mjs
@@ -0,0 +1,40 @@
+import { bench, run } from "../node_modules/mitata/src/cli.mjs";
+
+// pure JS implementation will optimze this out
+bench("new Headers", function () {
+  return new Headers();
+});
+
+var big = new Headers({
+  "Content-Type": "text/plain",
+  "Content-Length": "123",
+  "X-Custom-Header": "Hello World",
+  "X-Another-Custom-Header": "Hello World",
+  "X-Yet-Another-Custom-ader": "Hello World",
+  "X-Yet-Another-Custom-Heder": "Hello World",
+  "X-Yet-Another-Custom-Heade": "Hello World",
+  "X-Yet-Another-Custom-Headz": "Hello Worlda",
+});
+
+bench("Header.get", function () {
+  return big.get("Content-Type");
+});
+
+bench("Header.set (standard)", function () {
+  return big.set("Content-Type", "text/html");
+});
+
+bench("Header.set (non-standard)", function () {
+  return big.set("X-My-Custom", "text/html123");
+});
+
+if (big.toJSON)
+  bench("Header.toJSON", function () {
+    return big.toJSON();
+  });
+
+bench("Header fromEntries", function () {
+  return Object.fromEntries(big.entries());
+});
+
+run();
diff --git a/packages/bun-types/globals.d.ts b/packages/bun-types/globals.d.ts
index 86eb4c3d1..e3b2e6a3e 100644
--- a/packages/bun-types/globals.d.ts
+++ b/packages/bun-types/globals.d.ts
@@ -326,6 +326,22 @@ interface Headers {
     callbackfn: (value: string, key: string, parent: Headers) => void,
     thisArg?: any,
   ): void;
+
+  /**
+   * Convert {@link Headers} to a plain JavaScript object.
+   *
+   * About 10x faster than `Object.fromEntries(headers.entries())`
+   *
+   * Called when you run `JSON.stringify(headers)`
+   *
+   * Does not preserve insertion order. Well-known header names are lowercased. Other header names are left as-is.
+   */
+  toJSON(): Record<string, string>;
+
+  /**
+   * Get the total number of headers
+   */
+  readonly count: number;
 }
 
 declare var Headers: {