A high-end lock is usually faster than a second rate piece. Fastest ever were the late flint locks by Manton and contemporaries. (Say 1810 -1825)
French cock, roller frizzen and inset breech all add speed....
When I say French cock, these were good because they stood up well to the short throw and V strong mainsprings used in these locks.
Good luck with your search, Robby.