So... I just encrypted my xoom and it seems to have slowed it down a bit, its sluggish (er) transitioning between screens. How the heck do I Unencrypt it? I can't find an option to do it...
You will need to do a factory reset to remove the encryption. Depending on how many apps and how much media you have loaded on your Xoom that may not be a "big deal." The factory reset will erase your "sdcard" contents (including the music that came preloaded - so you should be sure to backup anything you want to save).
If you have a WIFI Xoom there have been some reports that a factory reset deletes the Honeycomb YouTube app (and it is not in the Market). 3G Xoom's don't seem to have that problem.
BTW: All other reports I have read indicate that encrypting does not affect performance (except for the need to "log in").