Grab a jet (I tried it with Wipeout and Neophron) and put it (e.g. via Editor) to the rolling field (Altis or Stratis - no difference!).
Start the jet, take off and then start a dive-bombing attack while holding down the mg-fire-button of the jet all the time.
When you´re very close to the ground, pull up the jet (while still firing) and the fps should instantly drop very heavy.
I can reproduce this all the time and right after pulling up and 2 to 3 secs of stuttering I have instantly normal (high) frames again.