Do you find that opening a new tab in Terminal, or iTerm takes a long time? Maybe 5 to 10 seconds, instead of being nearly instant?
If so, you may want to take a look at Apple’s syslog replacement called ASL.
ASL stores its logs on OSX Lion, under /var/log/asl/.
When Terminal or iTerm open, by default the execute:
login -fp <username>
This (for whatever reason) seems to read all of the log files under that directory. If like me you have 300Mb of rotated log files in there since your last reboot, opening a new shell can take quite a while.
I don’t know what the impact of deleting the files is, but given that they’re log files I deleted the rotated ones anyway. So far, so good! Shells open quickly again!