[Dovecot] RC16 is a lot slower that RC7

I tried RC16 from RC7 and like other releases since RC7 it is significantly slower. I'm still trying to figure out why. But I have again switched back. Do new version take up a lot more ram perhaps? I'm running with a gig of ram, and I'm running a few other apps. It's not a fast computer, just an old 754 pin semptron. But the point is that RC7 runs a lot faster than RC16.