I have rb750g3 with 4 kernels by 880mhz. The only speed i ever seen - 350mb/s on gigabit channel
through the router to PC. Meanwhile the CPU on router loads only for 30-40%. Is it some program restrictions of ROS?
If i connect cable directly to PC - can see 600-800mb/s on same tests (speedtest.net).
Expect between 400 and 800 with the hex. You wont get full gigabit.
Depends on the number of rules and how they are setup.
600 should be attainable, so yes you do have issues.