I would recommend you to use O&O defrag. It's quite useful.
In addition to your posts, when Fragmentation level increases, and you find it yourself by the change in the response time of the computer, it is too late and Defrag won’t help too much. Each time you store a file on a hard disk, the computer saves the new data on your available disk space, which may cause its existing files to get scattered across the disk.This can cause computer loading latency, you need to defrag your computer from time to time to avoid massive slow down.
Thank you another additional knowledge for us. keep up the good work!