The X11 driver seems to be running into a performance regression:

X11 applications will call glXChooseVisual at the very start of the process, to set up for X11. Calling this has become _very_ slow - so slow, that on fast hardware it delays starting every single X11 process by about two seconds.

I am reproducing this on Fedora Linux (38 or 39) with the following simple steps:

ltrace -T --output=ltrace.log glxinfo64 -B
grep glXChooseVisual ltrace.log

This yields

glXChooseVisual(0x55b51abe2da0, 0, 0x55b519abb040, 0) = 0x55b51ac03f00 <1.657946>

with the number at the right flagging: 1.7 seconds startup delay from calling a function, where the call should effectively be "free".

Now, this is not a problem under Wayland - but I cannot use Wayland right now (no fractional scaling; challenges in interaction between KDE and VMware graphics stack)