My Computer Runs very Slowly
Your computer will run slowly when it runs low on resources - too many program using too much memory or CPU time.
Viruses love to use as much CPU time as they can, and this is the usual cause.
Web browsers can consume large amounts of memory. They use it for a "memory cache".. A copy of webpages and images you have recently viewed are stored in memory so that the next time it is needed, it is displayed instantly, instead of going off to the website and downloading it again.