To test speed in the game take the quick mission flying over water.
But chose one of the bomber, Ju88, He111, Br20, or my favorite the Blenheim IV.
Fly low, very low, less than 300feet or 100 meters.
Make a track and look at it.
Change the position to the bomber crew in the nose of the plane.
Staggering how lower how better.
Have a nice game.