The FPS depends on more things:
1) Server latecy
2) Your hardware
3) Your internet connection
4) Gameplay environments(i hate this worddd)
1) Depends on how many and fast data you get from the server.
2) 128 MB onboard should be enough for minimun system requirments

3) You need 1 MB/s up and down(recommended).
4) If you are in gate your are going to have highest fps rate than on the normal maps. The real test is when you are going in invansions. If the number of ships is going to be more than 25 and when everybody will be in fight your fps will go down dramaticly, even with 10-20 FPS!!!