^+1
Also scan for malware.
If you don't already have it, grab a freebie system utility like Ccleaner and use it to clear out the various Temp folders Windows creates and fills with garbage, these are a common hiding place for low level malware and other unwelcome visitors. Only download Ccleaner from the Piriform website, more than a few hosting sites will give you unwanted or even nasty addons to the download.
If the problem persists, run Task Manager (Ctrl+Alt+Del) and see if anything is using a lot of CPU time or other system resources.
Otherwise, usual rule applies; run the system as clean as possible: Disable any software you don't need for the game/s, cull out any unwanted startup programs, don't play with a web browser open.