Having heaps of trouble enjoying the Alpha online with other players. The best I've seen is 32 FPS. THE best. The average I have seen in frames per second is 11.
Eleven FPS is far too low to test out anything, as even accessing the inventory, driving vehicles, checking performance changes, or simple combat is a non-starter.

I have high hopes for Arma 3, and while I DO realize this is in the Alpha stage (at time of writing) the performance issue is a definite problem.