I'm having problems getting the rocket to orbit reliably using Mechjeb. I'm using a macbook pro to play the game so even with the physics tuned all the way to the right it is slightly laggy so I have not tried manually flying it up to orbit yet. Any thoughts on what the problem might be? Mechjeb seems to want to constantly burn to round out the orbit, no burn to raise apoapsis and then coast and burn again. Just one long burn.