Been looking at the Combat attacking timer using Combat Demo Huge.
The component update itself is around 100ms/turn at peak, so the pathfinder is not the only issue there.
Specifically on the combat timer, finding new targets is by far the slowest, then it's a combination of the rest. Could be optimized by removing redundant checks, mostly, and improving QUeryInterface I guess. A particular source of slowness is TargetKilled, because of the two calls to the statistics (I think the query interface through player ID are particularly slow).
Interestingly, the slow part of finding new targets is the JS AttackTargetByPreference more than the cpp, which is reasonably quick in comparison.