denoland-deno/tools/bench/README.md

Re-bootstrapping

Re-bootstrapping allows deno devs to bench/profile/test JS-side changes without doing a full cargo build --release --bin deno which takes roughly ~4mn on M1s more on other machines which significantly slows down iteration & experimentation.

Example

import { benchSync, rebootstrap } from "./tools/bench/mod.js";

const bootstrap = rebootstrap([
  "webidl",
  "console",
  "url",
  "web",
  "fetch",
]);

benchSync("resp_w_h", 1e6, () =>
  new bootstrap.fetch.Response("yolo", {
    status: 200,
    headers: {
      server: "deno",
      "content-type": "text/plain",
    },
  }));

This code can then benched and profiled (using Chrome's DevTools) similar to regular userland code and the original source files appear in the DevTools as you would expect.