1. Use disk cleanup and disk defragmenter. Also, check your hard drive for errors.
2. Disable file indexing by right clicking on your hard drive and clicking properties. Uncheck file indexing at the bottom of the general tab. Also go the tools subheading at the top of your screen, click on folder options, and disable searching for network drives and printers every time you open a new window.
3. Download and run an antivirus program (although antivirus programs do slow down your computer a little bit, they clean up a lot of spyware and viruses that would slowdown your computer a lot). A good antivirus available for free is Avira Anti-Virus.
4. Remove useless programs from your computer by uninstalling them through your control panel. Also install Windows Care for free to speed up your computer through cleaning up the registry, removing spyware, removing temporary files and more. I also highly recommend system mechanic although it is not free.
5. Adjust your operating system for best performance rather than best appearance.
6. Download a program like Quick Startup to stop programs from initializing as soon as you start the computer.
7. Turn off error reporting and if your computer gets hot quickly, download speedfan to make the fans in your computer spin faster.
8. Disable your operating system's indexing services as they may slow down your computer.
9. Install updates for your operating system and remember to always clean your computer case yearly and to make sure your hardware is running to its full potential by downloading updated drivers.
10. If you really want to have a speed boost, reinstall your computer with the operating system and only the programs that you need.
11. Turn off excessive services running on your computer by clicking the Windows key and R, and then typing in services.msc and pressing enter. Some services that you may not require are: Alerter, Application Management, Clipbook, Fast UserSwitching, Indexing, Messenger, Net Logon, NetMeeting, QOS RSVP, Remote Desktop Help Session Manager, Remote Registry, and the SSDP Recovery Service.
12. Clean the Prefetch directory. Go to Start, Run, type in Prefetch and press enter. Select all of the shortcuts and then delete them. Please note: You must have an administrator account to do this.
13. Add RAM to improve the loading time of some applications.
14. Update your computer’s drivers including (if applicable), the computer’s: video card, sound card, and network adapter driver.
15. Upgrade the cables in your system. The smaller the cables that make up the larger IDE/SATA cables, the faster your computer’s connections become, as well as your computer’s performance.
16. Do not partition your hard drive. An unpartitioned hard drive is a lot faster than a partitioned one. Also, try not to use one IDE/SATA cable to connect two computer components.