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, Droid 2, Droid 3 and Droid 4 (all rooted)
Motorola Moto X DevEd - KK 4.4.4 + Root
Google Nexus 10 - KK 4.4.4 + Root