@dfordivam I see slowdown, occasional lockups. Almost 100% sure, I am using it wrong and not MVar's fault.
I haven't used chan, but want to use it. Currently playing with MVars and see if it fits the bill.
Functorrent has proved to be an awesome learning project for me. There are tons of things one can do and experiment with.
I am currently implementing the UDP tracker protocol. After that I hope the client will be more usable. Once that's done, I am going to pause and add tests. Also planning to implement a tracker server as part of testing.