Rodolfo Gouveia kindly did some tests on the tcp performance after the diff with gigabits ifs. Apparently there was a significant drop in performance (from 950mbps to 750mbps) after the change from poll to libevent, I'm not sure what caused the drop but it's on the receiver side, so my first suspect is kevent, than the libevent overhead.
Would be great if people could test tcp mode before and after the patch, also try running the patched version with: export EVENT_NOKQUEUE=yes This should make libevent fall back to poll(2) as noted by nicm@. If you can please, run the tests and send over, unfortunately I don't have gigabit interfaces.