re: Chatzilla...
I had disabled mine for quite some time now, probably around the time we were doing the FF 45.x testing. I seem to recall that it was positively identified as causing the CPU spikes.
Alright, but this post's conversation sort of re-kindled my interest in the good ol' IRC days. So I re-enabled it, using 0.9.93 version here. For whatever reason I do not see any CPU spikes here. Maybe it is the mix of the parameter changes I had previously implemented to deal with the overall FF CPU usage?
Anyways, @Dave, 0.9.93 working fine here, I did not attempt to replace the file with your version either.