Updated Arch from Plasma 6.3.4 to 6.4.5 in September. Ever since, I’ve had crippling intermittent mouse lag. Generally, it will flare up almost immediately using any web browser, and disappear shortly after switching focus away to anything text-based. Seems like it correlates with graphics load.
Search for a solution led me to https://bugs.kde.org/show_bug.cgi?id=472663. Re-enabling buffer readability checks (KWIN_DRM_DISABLE_BUFFER_READABILITY_CHECKS=0) tentatively seems to have it sorted, or at least substantially reduced.
If I’m understanding the discussion in that (and linked) pages, the referenced change works around a GuC bug upstream. My Intel GPU is too old for GuC support. Presumably any system running a pre-GuC Intel GPU would also be susceptible to my problem, and want readability checks enabled.
Should I open a bug to this effect? Or am I not fully understanding the situation? TIA.