If ICS seems slow you should do a Factory Reset first before anything more extreme like trying to go backwards to a previous version.
The same things were happening when the Xoom was upgraded to ICS......a few had issues with it feeling slower while the majority were raving about the increased performance. A Factory Reset corrected the slowness and/or FC's on most of those.
I personally always Factory Reset when changing/upgrading ROM versions (Eclair to Froyo, Froyo to Gingerbread...and now Honeycomb to Ice Cream Sandwich). Seems to keep the issues to a minimum.....
(just purchased a Transformer for my wife....)
Motorola Droid - SnkBitten 2.2.6 - Froyo
Motorola Droid 3 w/root - Gingerbread
Motorola Droid 4 w/root - ICS
Samsung Galaxy Tab 10.1 - ICS
Logitech Google TV - Honeycomb
Motorola Xoom w/root - JB 4.1.2
ASUS Transformer - ICS
Viewsonic Gtablet - *beta JB*
Google Nexus 10 - JB 4.2