I have to agree, you should see some difference, but not like that huge. Interesting I had a similar problem on an iMac, which Apple ended up replacing. I'm not that tech savy, but they said something about the Bus Speeds were not right revealing some problem that would require a complete computer replacement. I was happy, I got a new computer, but it was a pain to actually prove my computer was running really slow. However, that may have nothing to do with this, just my two cents.
Thats interesting. I should figure out to test my computer with benchmarks etc to make sure its all normal.