Dave_Hybrid - 11:07 am on Dec 7, 2009 (gmt 0)
I think someone posted earlier the speed was calculated from users toolbar data. So it is an average from users all over the world on all kinds of connections. I also think it takes a few days for changes to filter down. At least that is what I found with crawl stats, like a 5 day delay if I reduce page sizes to see lower crawl times in WMT.