I have no idea what they did, but Opera became slower and the routines for drawing the screen were all messed-up.
It took me less than a full day of use to decide to ditch it, it was that bad.
Rather than go through the hell of rolling back, I decided to give Firefox 3.6 a try.
It’s not as fast as the first iteration of Opera I had (which was heaven!), but it kicks the asses of both Chrome and Safari.
So, for now, it stays.
As they say, YMMV.