I use two 4K monitors. Haven't really had an issue with movement speed. I can pretty easily send the pointer from one side all the way too the other with one fl

I use two 4K monitors. Haven't really had an issue with movement speed. I can pretty easily send the pointer from one side all the way too the other with one flick of my thumb. I use sway/wayland though, so maybe it's different from X11 on that. I also mostly use the keyboard for desktop navigation, coding, etc. The mouse is almost entirely for clicking on things within a browser window and the occasional Steam game.