Twice in the last two weeks, I have seen an SfB Persistent Chat server go bonkers over a topology publish action. Specifically, it would seem that the topology publish action caused channelservice.exe to peg the CPU at 100% with the predictable result of a very sluggish server.
Tangential input and possibly related data points:
The fix was easy enough, in one case I did a stop-cswindowsservice followed by start-cswindowsservice. In the other case I had to boot the box because PowerShell opened but never responded to any input.
Such is life.