Yes, you should use a system monitor like "top" to see what is slowing down your computer. Some program/driver or misconfiguration could be causing the slow down. You could also check your sensors
to see if the computer is overheating, etc.
If you have a graphic driver issue try Mint with XFCE or LXDE, they are faster, less demanding and easy to make faster: viewtopic.php?f=42&t=96465