I'm gonna have to change my previous answer. My previous answer is much less than it is now. After messing with these newer flight sims (namely Lock On), I have come to the conclusion that there is not enough FPS in the world today. You can be blazing along at over 130FPS, and fly through one fire from an explosion, and it will go clear down to 22FPS, and that is not smooth. I've managed to get it to recover quickly from that 22FPS, but 22FPS is still too low. To fly smoothly, the thing needs to stay above 60FPS. Anything less, and you can see the "frameage"...especially when you look at the edges of the screen when the aircraft is moving.
Conclusion: There is NEVER enough FPS for certain simulators...or "games". I hate using that word "game". hehe