I've got frontpage as chatterbox only, but a fair number on nonfrontpage nodes: XP Nodelet, Chatterbox, Voting Booth, PmDev Nodelet, Information, Personal Nodelet, Other Users, Daily Best, and Weekly Best (in that order). I don't see a noticable slowdown. I should suspect that only the ones that make external connections (everydevel, cpan, and probably somthing else I'm forgetting) would give much of a slowdown.