One quick suggestion is running sudo pacman -Sc. Also switch to flatpak on some apps since these are stored in /home. If these don't work/are not suitable to your situation, give more information like mentioned on the other comments.
Client-side anti-cheat should die. Learn to write good netcode and serverside culling instead (maybe also ai anti-cheat like how valve is doing and some other company I don't remember)
No, i don't care how your internet sucks, dial-up is outdated.
The client is NEVER to be trusted, no matter the scenario. Get your shit straight.
FINALLY! SOMETHING FUNNY FOR ONCE!