After reading your BPM Detection Software page of September 2010 bought and registered a copy of BPMer 1.1.11. Big mistake. My iTunes library currently contains 15440 titles. After BPMer ran over night I found only 969 of them were updated with the BPM. After spot checking the calculated BPM was not accurate.
I have a Mac Pro 2x quad core with 6 GB, more than enough power for this app. So that surely is not the issue.
After experiencing the extremely poor performance of BPMer I would go so far to say that this product is not only unsatisfactory but borders on being an outright fraud. As such, i would urge you to not recommend it on your site.