fit-textareas causing major performance issue when typing in PR description textarea with Chrome

[with-heart]

With the fit-textarea feature enabled in refined-github@21.4.23, I'm experiencing a severe performance degradation when typing in a PR description textarea. Each letter appears to be taking ~500ms to be handled, making the feature unusable as it takes multiple seconds for a few words to appear.

Performance profile shows this line taking 1.5s per call:

Disabling the fit-textarea feature removes the delay.

I've uploaded the Chrome performance profile json file here: https://gist.githubusercontent.com/with-heart/f0d3b0914d2c25e6f635d82f91404e10/raw/af6e016d11ddf07e73a4459a6f40b1cc4ad58885/refined-github-performance-profile.json

This issue appears to be related to #4266.

[fregante]

Is this something that changed in the last release? Can you post a link to an affected PR? I see this

[SimenB]

I'm seeing the same thing (or rather, the slowdown. I haven't profiled it). E.g. in jestjs/jest#11033, but it happens in every PR for me (although the lag/delay gets worse the larger the diff is). This is using 21.4.23, which I think is the latest?

Disabling the fit-textarea feature removes the delay.

Same for me 🙂

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Testing in a larger PR at work - just hitting record in performance tab and writing "asdasdasdasdasdasd" takes 17s seconds to appear

Every keypress is 750-850ms

Horrible colors, but it say 7868.3

[fregante]

I'll revert this change in the next release, let's see how it will be.

The strange part is that .scrollHeight was actually in the previous version as well. This version was supposed to improve performance since it no longer resets the whole textarea every time: fregante/fit-textarea#15

I reopened fregante/fit-textarea#14

[kylemh]

I'm also seeing it a PR review comment textarea. It seems very heavy onFocus, onBlur, and on key stroke.

[yakov116]

We are going to revert the change in the next release.

[fregante]

Feature disabled via hotfix for the time being