Web-bugs: play.rust-lang.org - ASM tab is slow to scroll in Chromium-based browsers

[bvanrijn]

URL: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=932df557009ceff597e8f14321571d7f

Browser/Version: Chrome 79.0.3945.117 (Officiële build) (64-bits)

Operating System: macOS

What seems to be the trouble?(Required)

• [ ] Desktop site instead of mobile site
• [ ] Mobile site is not usable
• [ ] Video doesn't play
• [ ] Layout is messed up
• [ ] Text is not visible
• [x] Something else (Add details below)

Steps to Reproduce

1. Navigate to: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=932df557009ceff597e8f14321571d7f
2. Click the three dots menu in the upper left corner and choose "ASM"
3. Click "Show assembly" and try to scroll in around in the ASM tab on the right

__Expected Behavior:__

The site does not freeze up at all. Scrolling stays fast, and it's possible to keep using the editor.

__Actual Behavior:__

At first, scrolling is smooth but after a while, it starts to get slower and slower and the site freezes up more and more

Screenshot

[softvision-oana-arbuzov]

Thanks for the report @bvanrijn, I was able to reproduce the issue. On ASM tab scrolling is junky and even stalls.

Note: The issue is not reproducible on Firefox Nightly 74.0a1 (2020-01-08)

Tested with:
Browser / Version: Chrome 79.0.3945.88
Operating System: MacOS 10.15.1, Windows 10 Pro

Moving to Needsdiagnosis for further investigation.

[bvanrijn]

I should note it's also reproducible in Brave. It's not reproducible in Safari or Firefox, however.

[miketaylr]

Scrolling seems to be improved now, can you verify @bvanrijn?

[softvision-oana-arbuzov]

For me scrolling improved, it is smooth and fast as in Firefox and the site does not freeze anymore.

Tested with:
Browser / Version: Chrome 81.0.4044.129
Operating System: Windows 10 Pro