It's important to maintain our computer in order to increase the stability,speed and better response. Sometimes when we play a games its often to lagging, freeze, and even sometimes Blue Screen happen (Most of these cases caused by incorrect registry after uninstalling a program).
Here some tips from me:
1. Defragment your hard drive (especially drive C:\ or where the OS is Installed).
2. Remove/Delete some unecessary files.
3. CleanUp your registry, (a software required for this try this ccleaner cuz doing it manually quite confusing)
Thats the tips. The way I usually use though. :p