8.1 slows down CPU?

Hi, I've been running 8.0 on my tecra 8000 laptop (300MHz PII, 256MB) and it's worked quite well. Slower than my athlon desktop, but still quite useable. Now I've installed 8.1 and it's not quite fast enough to be used. I was about to revert to 8.0 when I noticed that yast2->hardware->hardware information reports that I now have a 137MHz PII. I'm not quite sure how it would be possible, but could 8.1 have changed the frequency of my cpu? To throw in another possibility, I had to install a new hard drive in my laptop when I changed to 8.1 because the old one was dying. Thanks, Steve