Your computer can run so slow if proper care is not done. The maintenance of computer is must and it should never be neglected otherwise you may not find the computer in a perfect state. If you are not taking care of your PC's health then it would not give you perfect output. You should analyze the reasons behind slowness of your computer. Hard disk is very important for the computer and if proper maintenance is not provided to the disk then there would some serious problems with your computer's performance. You should always check your disk for errors because there would be errors present on the disk without your acknowledgement. Checking the hard disk regularly will let you know the physical level of the disk and you can remove errors as well from the disk. 

One can also defrag the disk by using the windows disk defragmenter. It is available in the disk properties and you can improve the performance of your disk by utilizing it. This is one of the finest utility for the disk and in this way you can improve the overall performance of your PC. Surface scans can also be very good and it can be done through scandisk. It would be a through scan on the surface of the disk which can give very good results in the form of performance. There are some programs which are left in the memory and they are not closed completely. These programs may carry on using the memory along with disk resources. Most of these would be kept in the DLL files and all you have to do is to force these direct link library files being removed from the memory. It can also give your better outcome. 

This article is written by Jimmy Martin, who also writes for slow-computers.com, a site discussing slow computer performance, computer running slow, slow computer, and answering why is my computer running slow.