Check the malicious information to your computer. Note that if you need a computer for an extended period, you will ensure that your security software is up-to-date. So you can protect your computer from virus attacks well. If your PC is suddenly slower, can a virus or Trojan program of taking up their resources. You should check the anti-virus and to clean up open malicious files to test a slow computer.
It may be too many programs and processes running on your PC. These programs can start automatically when you restart the computer. They should not open many programs at once. As a result, your PC is working too hard. Therefore, the computer was slow. To increase the speed of PC, this is a great way to get the applications have not used the step-by-step instructions: Click Start> Control Panel> Add / Remove Programs> select Remove programs used