I have been reading the forums trying to find solutions to the issues plaguing my phone after the update the other day. I use my phone for business and cant afford these issues. The only solutions i have found is a factory reset. Really? The only solution is losing everything? Black Eye for Droid!!! It takes 10-15 seconds to actually go to the call screen after pushing call. it thinks for a minute and longer to open a email and then there is no option to reply to that email or forward it. it only allows you to read, delete it or mark it as unread. is there no other solution. besides getting an Iphone to avoid this in the future.
When did you install the update? If it has been greater then 72 hours (preferably longer) I would do a Phone Cache Wipe. This is NOT a FDR and you do NOT lose any of your data or apps or settings. This simply wipes out all of th stored in cache stuff which can include code from GB and other apps.
ICS will take a few days to optimize all of the apps and stuff you have on your phone, then it learns your patterns of usage to determine what to turn on or off etc... it only speeds up as you go along
After the Cache wipe, I have had NO issues at all with the phone.
if you have an android configured the way it's intended, you shouldn't lose anything at all. Make sure that you back-up your content and contacts using google (picasa or google+ for photos). As far as apps, they're easily recoverable in the Play Market and delivering them back to your phone is a snap using the online download (vs. using the phone).
what you are describing certainly sounds like you should do some kind of reset or refresh, it's unfortunate, but recoverable.