All computers slow down over time after being used. Saving files to the computer can bog it down, as can spyware, viruses and other malware. Even deleted files can leave residue on your hard drive. When you find yourself tired of waiting for your computer to carry out your commands, you can take action to clean the computer and make it run faster. Windows includes two important utilities for carrying this out: Disk Cleanup and Disk Defragmenter.
Eradicate spyware from your computer. Download and install a free anti-spyware program, such as Spybot Search & Destroy (safer-networking.org) or Microsoft Security Essentials (microsoft.com/security_essentials). Scan your computer using the program and delete any items it finds.
Run Disk Cleanup. Click "Start," "All Programs," "Accessories," "System Tools" and "Disk Cleanup" to open the Disk Cleanup utility. Check the items you want to delete and un-check any items you don't. Click "OK" and click "Yes" to confirm the operation.
Defragment your hard drive. Click "Start," "All Programs," "Accessories," "System Tools" and then "Disk Defragmenter." Select the drive to defragment. Click "Defragment disk." This process can take multiple hours.