Setting `macos_window_background_blur` above 0 leads to high GPU usage

[BhawickJain]

What Operating System(s) are you seeing this problem on?

macOS

Which Wayland compositor or X11 Window manager(s) are you using?

No response

WezTerm version

20240609-095134-f5e496eb

Did you try the latest nightly build to see if the issue is better (or worse!) than your current version?

Yes, and I updated the version box above to show the version of the nightly that I tried

Describe the bug

When setting macos_window_background_blur to any value above 0, it leads to my macbook to heat up and spin its fans up. The Activity App reports GPU usage of 20-40%. I have an integrated GPU.

To Reproduce

MacBook Details: MacBook Pro (Retina, 15-inch, Mid 2014) 2.2 GHz Quad-Core Intel Core i7 16 GB 1600 MHz DDR3 Intel Iris Pro 1536 MB (Integrated Graphics)

Configuration

local wezterm = require 'wezterm'
local config = {}


config.font_size                     = 16
config.font                          = wezterm.font('JetBrains Mono', { weight = 'Bold', italic = true })
config.hide_tab_bar_if_only_one_tab  = true
config.hide_mouse_cursor_when_typing = true
config.default_cursor_style          = 'SteadyBlock'
config.window_decorations            = "RESIZE"
config.window_background_opacity     = 0.80
config.macos_window_background_blur  = 30

-- old laptop friendy
config.animation_fps = 1
config.front_end = "OpenGL"


return config

Expected Behavior

I expect GPU usage to be relatively low perhaps under 10% when having macos_window_background_blur set to above 0. I also don't expect Window Server GPU to idle around 20%.

I have tried not setting animation_fps and front_end with no substantial difference in GPU usage.

Logs

Debug Overlay
wezterm version: 20240609-095134-f5e496eb x86_64-apple-darwin
Window Environment: macOS 11.7.10 (20G1427)
Lua Version: Lua 5.4
OpenGL: Intel Iris Pro OpenGL Engine 4.1 INTEL-16.5.14
Enter lua statements or expressions and hit Enter.
Press ESC or CTRL-D to exit
>

Anything else?

When I set macos_window_background_blur to 0, the Window Server GPU usage drops to single figures. window_background_opacity does not make any difference on GPU load at any value. I am switching from alacritty which has a boolean Blur option which does not cause the elevated GPU usage.