Zed/GPUI massively increase Hyprland's CPU usage

[adityasz]

Zed causes Hyprland CPU usage to increase from ~0.1% to ~9.5% (measured over 10 seconds):

$ perf stat -e task-clock -p $(pidof Hyprland) sleep 10

 Performance counter stats for process id '10632':

       952,042,695      task-clock                       #    0.095 CPUs utilized             

      10.002466604 seconds time elapsed

The hello_world.rs GPUI (Zed's UI framework) example increases Hyprland's CPU usage to 6.8%.

Similar behavior on both RTX 3060 and Alder Lake iGPU (with VK_LOADER_DRIVERS_DISABLE unset or set to nvidia_icd.json).

If the Zed window is moved to a different workspace, CPU usage gets back to a normal level. So, this may have to do with rendering.

WAYLAND_DEBUG=1 output for the hello_world.rs example.

A discussion in the hyprland-dev Discord channel.

GNOME does not show an abnormal increase in CPU usage with Zed or any GPUI application running.

With shadows and corner rounding disabled, Hyprland's CPU usage with Zed open is ~7%. Blur was not used. The window is floating.

Steps to run that example application

$ cargo init asdf
$ cd asdf
$ cargo add gpui
$ wget -O src/main.rs https://raw.githubusercontent.com/zed-industries/zed/refs/heads/main/crates/gpui/examples/hello_world.rs
$ cargo run --release [--jobs <N>]

[adityasz]

This may be useful: gpui/src/platform/linux/wayland/window.rs

[vaxerski]

judging by the wayland_debug output it's just the fault of that shitass wayland impl (same problem cosmic's apps have) and not a hyprland issue, but I have no clue how to even build that thing so I can't say for sure.

[adityasz]

Added steps to run that example application to the original post.

shitass wayland impl

I don't know anything about Wayland implementations, but GNOME handles GPUI fine. But yeah, among Zen/Firefox, GTK, QT, JetBrains, and even Electron, GPUI certainly stands out. If you know what they are doing wrong, it would be great if you can tell that so that an issue can be created in Zed's repo.

[vaxerski]

god damnit I gotta install rust

anyways the bad thing is the display sync spam

[vaxerski]

yep just tested, lack of damage tracking and display sync spam. This is a toolkit issue.