jbb2005 seems to have taken two discrete hits over the past couple of months which leave us at 82% of our most recent best.
The following graph tells the story:
The first big hit was apparently due to the nano timer commit (r13209), which apparently jbb2005 did not properly recover from.
The second hit is a little less obvious (between r14403 and r14425).
Unless anyone has better ideas immediately, I'm prepared to take an exhaustive look at the revisions between 14403 and 14425 to try to get a clearer picture.