1920917 - www.capcut.com - Toolbar leaving a white trail when it hides while scrolling down

Status: NEW

(Core :: Performance, defect)

Description

[Calin Tanase (OOO until 22nd of Nov)]

Environment:
Operating system: Android 11
Firefox version: Firefox Mobile [phone]

Preconditions:

• dark theme enabled (it reproduces with light theme as well but its barely noticeable)
• "Scroll to hide toolbar" enabled

Steps to reproduce:

1. Go to https://www.capcut.com/ro-ro/
2. Dismiss the cookie banner.
3. Scroll up/down fast.
4. Observe the toolbar.

Expected Behavior:
There's no trail left behind when toolbar hides.

Actual Behavior:
Toolbar leaves a white trail for a very short duration when it hides.

Notes:

• Doesn't seem to reproduce on other websites
• Reproduces regardless of the status of ETP
• Reproduces in Firefox Nightly, and Firefox Release
• Does not reproduce in Chrome

Created from https://github.com/webcompat/web-bugs/issues/141969

Comment 1

[Calin Tanase (OOO until 22nd of Nov)]

Attachment: Toolbar.mp4

Comment 2

[Dennis Schubert [:denschub]]

This is the most minor if minor performance issues, but it technically still is one.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

This bug was moved into the Performance component.

:ctanase, could you make sure the following information is on this bug?

• For slowness or high CPU usage, capture a profile with http://profiler.firefox.com/, upload it and share the link here.
• For memory usage issues, capture a memory dump from about:memory and attach it to this bug.
• Troubleshooting information: Go to about:support, click "Copy raw data to clipboard", paste it into a file, save it, and attach the file here.

If the requested information is already in the bug, please confirm it is recent.

Thank you.