I feel your pain (just look at Parrot's test suite, and then compare it to the Pugs test suite...), but everything I've seen you write publicly about speeding up your test suite has been microoptimizations that gain you five seconds here and ten seconds there.

Now I'm obviously not privy to the details, and you may have 500,000 assertions that run in 11 minutes (which is a pretty good clip), but my instincts tell me to look for the equivalent of algorithmic improvements, not two and three percent here and there.

I don't remember the name of the health insurance billing project you saw me work on, but I did a brief statistical analysis of their test database, dropped 90% of the records, and cut the running time of certain tests by an order of magnitude. I hope you've looked at those types of optimizations and are just doing cleanup now.