Defraggler will warn the user when the Recycle Bin should be emptied first to save time. However, it seems to do only that - and if the Recycle Bin has a lot in it, the process will freeze while the thread runs. CCleaner doesn't freeze, is much more comprehensive, etc. - given that both are Piriform products, if both are installed, why not have Defraggler offer to open CCleaner instead?