|What other housekeeping tasks have you not been doing?|
Slowness can also be caused by other factors such as the kind of antivirus/antimalware programs you are running, and the number of other programs & processes running in the background. You also appear to have a system with only 512mb ram with 64mb of that being used by your graphics.
Without a detailed list of the software & processes running on your system we have little information on which to base recommendations.
There is no need to worry about where deleted items have gone. If they are not in the recyclebin ( where they would be taking up room on the hard drive) then the space they were occupying on your drive has been freed up. A defrag might help a little.
Goin' Fishin' (Some day)