So, I think it is safe to presume that a fully-loaded ROM, with ActiveSync and Microsoft Live both doing push, a weather program pulling updates and an RSS reader, polling for updates ... are all going to impact performance!
It's an interesting question, though: Do you want to know how well your device is capable of performing, with a bare-boned ROM (not particularly useful) or loaded up as you would use it on a daily basis?
Be right back ...
Best regards,
-boggsie