I also bought the imagio on day 1. My phone became progressively more laggy as time went on. It was really annoying as my phone started to take about 4-5 minutes just to start up!
Here is what I did to fix it.
1. Use My Phone to backup all your contacts. This makes it a snap to re-populate your contact list.
2. HARD RESET my phone to remove all the crap that is making it laggy.
3. Install all core type of CAB's directly into the phone storage. One example is Compact Framework 3.5. If you install it to your micro SD card, an app that uses its API is considerably slower.
4. Install all other apps 1 by 1 and test to see if it gets laggy after each one is installed. If so, then you found the issue.
5. Once all apps are installed, cross your fingers and wait a few days (or weeks) to see if it is getting laggy again. So far, I haven't gotten any lag.
I've spent HOURS trying to figure out issues for my phone being laggy. Trust me, a hard reset and re-installing apps is less frustrating. It took me about 1 - 1 1/2 hours to re-install and reconfigure everything and now my phone runs SPEEDY
.