COSMIC 1.5 prevents its panels from eating your CPU while your PC is locked

COSMIC is quickly becoming my favorite desktop environment, but it is by no means perfect. However, it is not due to poor programming; It only got its first stable release in December 2025, so it still needs some time to mature and receive bug fixes. Such is the case of COSMIC version 1.5, which fixes some nasty problems like panels hogging your CPU every time you lock your computer.

Turns out COSMIC panels didn’t like it when you locked your PC

How he saw it LinuxiacCOSMIC Desktop has been updated to version 1.5. The new version brings some interesting changes, such as allowing users to save 500 wallpapers instead of 100 and allowing people to add multiple images at once to the wallpaper list. Additionally, the shiny new frosted glass theme works on applets connected to a hot-pluggable external monitor and will no longer flicker when maximizing a window.

However, the tweak that caught my eye was one titled simply “Fix High CPU Usage When Screen is Locked” in the Cosmic Panel category. It turns out that when you lock the screen, the COSMIC panels go into a loop:

is_dirty it is deleted only in render but when the screen is locked we don’t get any rendering callback. So, is_dirty remains true and we are stuck in a rebroadcast loop.

I introduced a new flag that clears needs_layout so we don’t redo the design, and is_dirty will be deleted whenever render.

COSMIC Desktop 1.5 is available for download, so get it from the GitHub page or update it through your distribution’s usual channels. And if you’ve never tried COSMIC before, be sure to check out why I’m starting to like it more than KDE right now.