I have noticed lag in Retroarch and other programs and think that since optimus-manager gives an error at the command line, Manjaro isn’t picking up the NVIDIA card for some reason. This happened after some kernel upgrades, and I recently had an issue with a bad superblock on the install partition, but I fixed that myself. The terminal output from optimus-manager is as follows:
ERROR: the latest GPU setup attempt failed at Xorg pre-start hook.
Log at /var/log/optimus-manager/switch/switch-20211008T101634.log
Cannot execute command because of previous errors.
Paste of the log here.
I also had issues removing the old kernels from the kernel manager GUI due to what I think was the bad superblock. Fixed that as well.