When I am using iTerm 0.10 with two or three windows open with three or four tabs open in each, I am noticing that things will work fine initially. However, if I come back a day later to the same sessions, the keyboard response will start to become sluggish and sometimes when I try to select one of the tabs, it will appear to hang up for 10 or 20 seconds before I get a response.
When I downgraded to build 0.9.6.20090928, the problems went away.
I'm having the same issue since upgrading to 0.10. I've been using iTerm daily for at least two years on the same computer (Mac Mini PPC G4). iTerm, VNC server, and activity monitor are the only apps running on this system. I typically have about 6 tabs open in one window and 3 to 4 tabs open in a second window. After sitting for 2 days over the weekend iTerm was using 40%-80% of the CPU with no input or output in any of the sessions. I began killing sessions one by one. When I was down to one session iTerm was still using about 40% of the CPU. Once I restart iTerm thing seem OK for a week or two then it starts using way to much CPU and it becomes sluggish. I think it's time to go back to 0.9.6.
I downgraded from 0.10 to 0.9.6.20090927 (intended to use 0.9.6.20090928 but the download link took me to 0.9.6.20090927 instead, weird?). Same problem, opened two windows, one with 6 tabs the other with 3 tabs, used it for 5 days straight with no problems. After letting the system sit idle for 2 days iTerm is now using about 70% of the CPU when doing nothing (well I guess it's doing something :-) but I can't tell what) So the issue is not specific to 0.10. I'm running OS X 10.5.8 on PPC G4.
The iTerm project is no longer being maintained. This is a known bug in iTerm, and has been fixed in iTerm2. Please visit the new project at http://iterm2.googlecode.com/.