8 hours to encode 90 minutes on a single processor 1.25Gh machine is not out of the realm of reality. My dual 2Gh G5 takes about 5 1/2 hours for the same amount fo footage.
I’m having the same problem. No matter what bit-rate I use in Compressor 2.x, I get blocking and bad artifacts whereas the same bit-rate in Compressor 1.x yielded much better results with similar footage.