Big delay looking up blogs with wpmu versus buddypress


I've got two blog servers running. I've been optimizing them, and just noticed a big performance difference between the Buddypress installation and the regular blog server not running buddypress – amounting to an average of 5 seconds delay, apparently for the main blog to look up the sub-blog.

The difference is striking – And I'd sure like to fix it.

Here is the time analysis for the regular blog – note the 6 seconds to access the original blog versus the speedtest-1 (hosted under buddypress):