Some of the best ways to speed up a scan without having to upgrade any hardware is by:
(1) As stated above, defragging.
(2) Clearing all temporary files. This will reduce the number of files to scan.
may I add some too?!!
3. Disabling those windows services which is not needed (there are a lot of!)
4. choose stand-alone program instead of programs which has alot of background services.
5. use less programs in windows startup. run programs manually after windows boot time.
6. use latest version of updates hardware drivers.
7. keep computer/laptop bios up to date.
8. use cheap things to speed computer. for example windows readyboost is one of them that works with normal flash drives.
9. use tiny program when there are instead of using heavy program in computer.
and a lot of other...
Yeah you are entirely right but if I clean all the errors will the scan be quicker?
sometimes it can help, but you should review every key that you are removing, because sometimes they cause problem more than what they fix.