[Bug]: devtool extremely slow with @remixicon/react

[dave-dashbio]

System Info

  System:
    OS: macOS 14.4
    CPU: (12) arm64 Apple M3 Pro
    Memory: 70.66 MB / 36.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.16.0 - /usr/local/bin/node
    npm: 10.8.1 - /usr/local/bin/npm
    pnpm: 9.6.0 - ~/Library/pnpm/pnpm
  Browsers:
    Chrome: 132.0.6834.111
    Safari: 17.4
  npmPackages:
    @rspack/cli: ^1.2.2 => 1.2.2
    @rspack/core: ^1.2.2 => 1.2.2

(Same issue in a Linux docker container as well.)

Details

rspack has been fantastic so far! However, I ran into an issue once I tried importing from @remixicon/react. The dev server startup speed grinds to an extremely slow ~40s (but HMR is fast afterwards).

I stripped it down to a minimal repo. My rspack.config.cjs is:

const { defineConfig } = require("@rspack/cli");

module.exports = defineConfig({
	context: __dirname,
	entry: "./main.js",
	devtool: "eval-source-map"
});

And main.js is simply:

import { RiHeartFill } from "@remixicon/react";
console.log(RiHeartFill);

When I run in dev mode with rspack serve, it succeeds but incredibly slowly:

Rspack compiled successfully in 38.91 s

If I set devtool: false, it is much faster:

Rspack compiled successfully in 212 ms

Reproduce link

https://github.com/dave-dashbio/rspack-devtool-issue/tree/main

Reproduce Steps

pnpm i
pnpm dev