Extreme lag since updating to 10.8.1

I have a Mac Mini 2.3 GHz Intel Core i5 with 8GB of ram that ran like a champ up until the very latest update of Mountain Lion 10.8.1. Since then, it is agonizingly sluggish.

The mouse always plays 'catch-up' with me if I move it around too quickly, using the Internet is an exercise in frustration as my Mini just sits and thinks about the link I've just clicked on, then finally begins loading the page but at such a slow rate that I'm almost convinced I'm back in the bad old days of 56k dial-up (heck even that seemed more peppy and responsive now that I think about it). Once a page begins loading, I can't do *anything* with my Mini till it is finished, usually between 30-45 seconds later. It is the same whether I'm in my favorite browser Chrome, or Safari or Firefox or even Aurora.

Don't even get me started on the near-tears I'm brought to when I fire up iTunes or iPhoto. 😢 Is my extreme performance degradation isolated or is there something going on with anyone else?

Oh yes, I have ran Disk Utility and it states everything is fine. I make sure I run only 1 app at a time just to make sure system resources aren't being hosed for some reason, but I've ran out of ideas.

I just don't understand why a simple update would have so completely ruined my user experience? Mountain Lion 10.8.0 was just fine.

Help!