Using my newbie's rights to post questions anywhere I can

In Windows there is a registry, which has information about installed programs (and there is many other things, ofc). And sometimes it's useful to reinstall Windows because registry becomes large and slow.
As far as I know, Linux has no registry (yes, I know, that Slackware has information about all installed packages, but, I think, it's used only when you try to delete package). So, my question: does large number of installed packages decrease my PC's performance?