Even if your computer is state of the art, it will tend to run slower over time. You notice that the programs are getting stuck and the operating system is slow to load. In these and other cases, you need to find a way to un-clutter your PC and boost its performance. Here are some suggestions.
Run Your Anti-Virus Program
You may not know it, but your computer might have contracted some worms and virus that suck the bandwidth quietly to the extent that your PC runs at a snail pace. A short system scan might not remove these viruses, but a full scan with your computer on a Safe Mode will wipe them out.
Run Spybot or Lavasoft’s Adware Program

When pop-up ads appear randomly, or when your web browser shows a new shiny and useless toolbar, there’s spyware in your PC that should be swept away. These tools are free to download, and they will get rid of spyware and the clutter, so your computer will be performing at faster speed.
Perform a Defragmentation
This task will free up your computer memory. Because defragging the hard drive may take a while, you can do it overnight. Then, add more memory. If you have only 256 RAM, you can upgrade it to 512. If you have more memory, your machine will run faster. The new computers built today have no less that 1 GB of RAM, so they are faster than the earlier built computers.

Remember, if your computer is slow and you want it to run faster, don’t be tempted to work on it yourself, unless you are sure you know how to do it.