I personally have used RCS in the past but haven't in a few years now, they have the potential to take out
files that are needed in your system, I wouldn't bother with them at all for this very reason, if you think by
cleaning your register from files that aren't being used is going to speed up your system this a very non issue
for the simple reason computer hardware components are much faster now as opposed to in the past.
I get all kinds of insight into computers by my brother who is an IT professional and owns and operates his own store.
IF you really want to speed up your system try upgrading your CPU , hard drive and RAM instead.