According to CNET News.ocm, Google've started giving priority by web page loading speed. You can also find this new policy on Inside AdWords blog.
Google seems to apply the 3rd thing (namely, Fast is better than slow) in Ten things Googl has found to be true.
As a result, high page loading speed may get higher Quality Score, while low page loading speed may get lower Quality Score. And as you guess high Quality Score lower minimum bids.
How about checking your web page loading speed using such as SELP SEO's Free website speed check?
