It's not hard to think up reasons why cleaning up unused hard drive files, the unwanted or unused ones, is a good plan. The overall performance of your computer, particularly while accessing disk files and documents can be a function of the total file count stored in its file system. The reason for this behaviour is that with more stored files, the FAT (file allocation) tables grow and the system has to do more work each time a file is accessed. Due to the mechanism whereby file data is stored on the disc surface, file continuity is disrupted and this causes read rate to decrease. Additionally keeping private files private is more difficult, as you store more and more of your private files (banking, identification etc) there is the possibility (no matter how remote) that somebody else using your PC will find them. Additionally, cleaning up files can return free space to the available data pool which is better for obvious reasons.