ath performance degradation between Oct-12 and now?

[Sven Hazejager]

I have just upgraded my ALIX router (with an Atheros 9160) from
FreeBSD-HEAD r241243 (Oct 6, 2012) to r247155 (today) and I am
noticing slightly lower throughput rates.

With iperf, sitting 1 meter from the router, I consistently get 79-81
Mbits/sec TCP with r241243. This "drops" to 74-76 in r247155 (never
higher than 75.5 actually). The rates also seem to vary a bit more
(but that's hard to quantify).

Anything I should be looking for? I'm more than happy to share debug
output etc. if instructed how to capture.

Thanks!
Sven