The responses to all 3 devices -- keyboard, joystick and mouse (I have no TrackIR, but I believe the problem would probably occur on it too).
It seems to be graphics problem. Because, the response is worst when using "F8" to view around the aircraft, also when heading down on massive targets. Sounds like insufficient RAM problem but, I don't think so. The FPS is very good everywhere in the sim, and around one year ago, I used GeForce4MX and the sim ran very fine, with slightly lower FPS than present.