FF 10 seems to be the problem Rated 5 out of 5 stars

I found that even without Nosquint installed, FF 10 was painfully slow, and some pages required repeated clicks to load. So I dropped back to FF 5.0, and bingo, pages load fast, and Nosquint seems to be working fine.

This review is for a previous version of the add-on (2.1.5.1-signed.1-signed).  This user has a previous review of this add-on.