Dump sigs if they increase load time. I used one the first month or two, but it got to be too much work to keep on thinking up new ones. Anyone who really wants one can type or cut and paste one in.
Likewise dump date registered and post count. They’re usually not relevant, and in the few cases they are they can be checked by clicking on the profile. That may cut down on stuff like post parties and post padding too.
Keep smilies though. A wink smilie can sometimes be essential in letting someone know you are joking and short-circuiting a flame war. In terms of cost/benefit I think they’re probably worth it.