Transmission daemon deadly slow!

i've been using transmission on my router for a while with very good performance and no problem at all.
Yesterday i updated my (custome made and with NSS) master to SNAPSHOT r23602-5a6e234661 and i wonder if i also got a new transmission version because definitely something changed: transmission is now deadly slow! as soon as i add a torrent i'm not even able to remotely connect to see the status of the torrent, in top it seems to totally eat one core and i can't do anything else with the router (files served by minidlna are dying after few seconds)
can anyone confirm? i have a custom build so i can't be sure about transmission problem, but i see the package was really touched some days ago so maybe it's really a transmission problem..