Many people have wondered the same thing, "Why is my computer so slow?" There are generally a few common reasons computers act slow. I've found that these three problems cover nearly all slow computers. Without further delay, here are the reasons.
1) You have Spyware problems. Spyware problems will really hurt your computer. Spyware keeps track of activity on your computer, such as internet usage. This is obviously not a good thing to have this spyware reporting how you use your computer. On top of that, having a lot of spyware really slows down your computer. Download A-Squared free or use the ewido online scan to remove them.
2) You have virus problems. I'm sure you've heard of viruses. Much like spyware they aren't good to have on your computer and really slows it down. Download AVG Free or run the BitDefender online scan to remove viruses.
3) You need more RAM (aka memory). Operating systems continue to get bigger and bigger and require more and more resources. To check how much memory you have, right click "my computer" and choose properties. If you're running Windows XP you want at least 512MB. You want 1GB for Windows Vista. If you aren't sure of how to buy or install RAM, ask your local computer repair shop to do it for you.
These 3 things will speed up almost any slow computer.