Defragment your drive: This is one of the often repeated tips, yet we say this again. . I think it is the most common reasons for making hard disk performance slow down. As the new files cannot be stored in contiguous clusters, the disk becomes fragmented when files are deleted and new files are written to the disk. Use the Windows defragmentation tool which comes default with your Operating system or a free tool like Auslogics Defragmenter which can be find here: http://www.auslogics.com/disk-defrag .
Avoid tilting : You should avoid this or otherwise moving your PC when the PC is on will led your hard disk to crush. Hard disks do not take too kindly to being moved around while they are working! And, if you hear a screeching noise from your PC that coincides with the hard disk activity indicator(usually the red or amber LED), it's time for you to backup immediately and be prepared for a new hard disk.