Very noticeable latency/input lag

I experience a very noticeable latency on Plasma. No difference between X11 (both with compositing enabled and disabled) and Wayland. A very rough estimate using a reaction speed test puts the latency at around 60ms (going from ~160ms on XFCE4 with compositing enabled to ~220ms on Plasma).

As an experiment, I downloaded KDE Neon and booted into the live session. This removed the latency completely, which indicates to me that this is not a hardware issue. I also tried reinstalling KDE and mesa, which did nothing.

kinfo output:
Operating System: Arch Linux
KDE Plasma Version: 6.0.1
KDE Frameworks Version: 6.0.0
Qt Version: 6.6.2
Kernel Version: 6.7.9-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 12 × 11th Gen Intel® Core™ i5-11600K @ 3.90GHz
Memory: 15.4 GiB of RAM
Graphics Processor: AMD Radeon RX 6600 XT

I managed to solve this. It turns out that the “Press left and right buttons for middle-click” option adds this delay to clicks, and the reason the KDE Neon live session worked fine is because that option is turned off by default.

I might just be very sensible to input latency, but I feel like this should be documented somewhere.

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Thank you for figuring that out!
37,5% increase in latency is a lot.

Could you please create a bug report about this?

No problem, I filed a bug report. (Bug 483093, not allowed to post links, sorry)

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