Describe the bug

I experience a longer delay than expected when loading a file using a JavaScript import :

const start = performance.now()

import data from "5mb-file.json"

const end = performance.now()
console.log(`Delay : ${end-start}ms`) // about 5s

The ~5s delay seems unreasonnable considering the size of the file.

For comparaison using JSON.parse and fs.readFileSync on the exact same file, I'm able to retreive the data in about ~0.1s.

Reproduction

https://github.com/mquandalle/large-import-delay-vitejs-repro

The reproduction contains 2 server-side endpoints showcasing the two import methods (ES module or JSON.parse/fs.readFileSync), and a minimal UI to explain the issue a bit more.

Logs

No response

System Info

System:
    OS: Linux 5.13 Pop!_OS 21.04
    CPU: (8) x64 Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz
    Memory: 1.63 GB / 15.40 GB
    Container: Yes
    Shell: 5.8 - /usr/bin/zsh
  Binaries:
    Node: 16.11.0 - ~/.nvm/versions/node/v16.11.0/bin/node
    Yarn: 1.22.15 - ~/.nvm/versions/node/v16.11.0/bin/yarn
    npm: 8.0.0 - ~/.nvm/versions/node/v16.11.0/bin/npm
  Browsers:
    Brave Browser: 96.1.32.113
    Firefox: 94.0

Severity

serious, but I can work around it

Additional Information

This issue occurs both on development mode and when the app is deployed and the import called for the first time (example: cold starts on Vercel lambdas)