I noticed a while ago that ActiveSync would start on its own, usually when turning BT/WiFi on. With it running, my Tilt is very sluggish to respond. I searched and found this tip at mobiletopsoft.com (it is for WM 5.0, but works with 6.0/6.1). I've modified it based on my experience.
1. Start ActiveSync and go to Menu -> Add Server Source
2. Enter a nonexistant email address and uncheck the the autodetect settings box. Click next.
3. Put in a fake IP address and click next. Then punch in fake info for the username, password and domain. Check the save password box and click next.
4. Uncheck all items in the "data you want to synchronize" box" and click finish.
5. Now go to Menu -> Schedule...
6. Change both the peak and off-peak sync schedules to Manual and click ok.
7. Do not delete the server like the mobiletopsoft.com page states. I did this and ActiveSync resumed its random startups. Leaving the server listed will keep this from happening, and if you unchecked all the items in data you want to sync box during setup, it won't bother attempting to sync anything with the exchange server when you sync with your PC.
How to prevent WM 5.0 and ActiveSync from draining your battery.