Tiny system hang when using a remapped key

[creeper82]

I have two mappings due to broken X and R keys on my machine:

Shift+Spacebar maps to R
Apps/Menu key maps to X

Might be crazy, but I got used to it. What is a bit unpleasant is that every time I press one of these, the screen freezes for some milliseconds (in some cases it feels like 300-400ms). When I type that remapped key several times in a row, it stops lagging, and freezes again when I use a normal non-remapped key. It feels like the transition from normal typing to using remapped keys causes a hang.

I use Arch Linux with GNOME 47.1 (but also happened on previous versions). Now I am on xorg, but it also happened on Wayland. Is it a known issue? I remember that Windows PowerToys key remapping tool for example had not even a slightest delay with the same key remappings.