I second the effectiveness of a regcleaner/reg defraggler
my old windows 7 desktop became really slow that disk cleaners and several reboots didn't help. I used reg defrag and it immediately fixed that problem
second time and third time with the exact same issue, registry defrag saved the day
I use CCleaner + CCEnhancer, DiskMax, Privazer and sometimes Wise Cleaner
Privazer seems to clean the least trash
sometimes, wise cleaner can clean several hundreds of MBs more after I use all other 3 cleaners