Scrolling lag on M1 Pro Max

[jhuckaby]

Type: Bug

1. Open text file (HTML, etc.).
2. Scroll using the trackpad -- keep your fingers on it (no inertia).
3. Notice the scroll lagging so badly it slows to 1 FPS or so.

Expected results: smooth scrolling.

Note: Opening a file with word wrapping makes the issue far worse.

VS Code version: Code 1.81.1 (6c3e3db, 2023-08-09T22:40:25.698Z)
OS version: Darwin arm64 22.6.0
Modes:

System Info

Item	Value
CPUs	Apple M1 Max (10 x 24)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: disabled_off direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled metal: disabled_off multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled
Load (avg)	2, 2, 2
Memory (System)	32.00GB (1.20GB free)
Process Argv	--crash-reporter-id bb8f29d5-8631-4571-84a5-eb72eadd2676
Screen Reader	no
VM	0%

Extensions (7)

Extension	Author (truncated)	Version
cpptools	ms-	1.17.5
sublime-keybindings	ms-	4.0.10
savebackup	pur	0.0.4
code-spell-checker	str	2.20.5
vscode-icons	vsc	12.5.0
vscode-todo-highlight	way	1.0.5
material-theme	zhu	3.16.0

Screencast

vscode-scrolling-lag-bug-720.mov

Notice the extreme lag on that relatively small HTML file. Now, here is the interesting bit. If I scroll with inertia (push the trackpad then release my fingers so the scroll coasts and glides to a stop), it's perfectly smooth. Shown here:

vscode-smooth-scrolling-with-inertia.mov

So, the issue only occurs when I scroll while holding my fingers on the trackpad, i.e. preventing inertia scroll.

Performance Profile Recording

Here is a profile I recorded while producing the scroll lag:

Profile-20230901T151227.json

It seems like the debugger thinks that VSCode is "idle" during the lag stalls.

[jhuckaby]

Note: Restarting VSCode fixes this issue.

[trodlermichal]

Same issue here and restarting the VS Code doesn't help at all. I am editing Jupyter Notebook file and it's never been OK.

• when I scroll to the very end of the file, i have to use slider to get back up, scrolling is of no use there

[alexdima]

Joseph Huckaby (@jhuckaby) Are you still experiencing this issue? I can imagine this being one of two problems:

1. the rendering of each frame is very slow
2. the events coming in from the browser/trackpad instruct us to scroll in this manner

Given that scrolling is fast once you release your fingers from the trackpad and that the issue disappears when restarting vscode, I am inclined to believe this is 2), which would be a problem with Chromium or with the hardware. But, to rule 1) out, could you please follow the steps at https://github.com/microsoft/vscode/wiki/Performance-Issues#profiling-the-renderer-process and share a CPU profile?

[jhuckaby]

I apologize for forgetting to update this issue, but the problem went away in one of the VS Code releases in 2024. Thank you for following up Alexandru Dima (@alexdima). I'll close the issue now.