3-10x slower performance in dev in Vite 5.0.3.

[cpojer]

Describe the bug

I updated Vite from 5.0.2 to 5.0.3 today and noticed my tests were timing out. I have custom infra using Vitest + Playwright to open a browser using Vite. Vite loads a few hundred JS files (~80k lines of code in this case) and renders some stuff with React. With Vite 5.0.3 it consistently takes 3-10x longer to load those webpages.

Here is a video: https://github.com/vitejs/vite/assets/13352/96ea4de5-2ed0-4f1f-8776-16fc30b4cc67

The first load is via Vite 5.0.2 and takes about 1.5-2 seconds. Then I upgrade to Vite 5.0.3, restart Vite and load the page again twice. Both times it takes 5-10 seconds. I don't know how to debug this further, and will appreciate any help to troubleshoot the issue and come up with a consistent repro.

Reproduction

CleanShot.2023-11-29.at.19.47.44.mp4

Steps to reproduce

TODO

System Info

Latest mac OS with latest version of every possible package.

Used Package Manager

pnpm

Logs

No logs.

Validations

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• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
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• The provided reproduction is a minimal reproducible example of the bug.

[patak-dev]

@sapphi-red we discussed in Discord and @cpojer found that reverting:

• fix: js fallback sourcemap content should be using original content #15135

fixes this regression for him.

[cpojer]

I can confirm that 5.0.4 does not have the same performance problem. Thank you for the quick turnaround as always 😍