Notebook slow scrolling caused by update layer tree

[rebornix]

Originally reported by @digitarald

Expensive layout is the cuplrit, even warned as layout shift so content really seems to move on every frame while scrolling – cased by a wheel event handler calling setScrollPositionNow.

After digging into the perf log, it seems there is a long update layer tree (~10ms) for every scroll.

[rebornix]

@digitarald can you try below when you get a chance to reproduce the issue

• run vscode with --disable-gpu and see if you can reproduce
• check if you have a large code cell (with a lot of lines), if so, try to split the cell to smaller cells and see if you still see the slowness

[claudiaregio]

+1

[claudiaregio]

+1

[alceballosa]

Hi @claudiaregio , I tried making a new notebook (using the disable-gpu flag) with only a few cells of code and one markdown cell, and the behavior is the same. Are there any other options I can test? To me it seems that it's not slow at all, only that the sensitivity of the mouse scroll goes up for those cells.

Thank you!

[rebornix]

@alceballosa do you have editor.mouseWheelScrollSensitivity for the text editor?