Lost 800 gb of space using defraggler in Defraggler Bug Reporting Posted January 8 - The combination of System Restore and Defraggler is Always a cumbersome one. This is known to slow down the defragmentation process. - Reduce the amount of disk space that can be used by System Restore. If that's at say 60% of total disk space then reduce that to e.g. 30% or whatever size/percentage you like best. - Run Antibody's WIZTREE. It will tell you what the size is of that folder called "System Volume Information". Give us that number. - Turn off "System Restore", restart your system and turn "System Restore" back on (if you want to). That should help to free up that used space.