Commentaire officiel
Your aircraft speed is likely limited by the speed of your camera and the SD Card Write Speed in the settings.
If you can only write one file every 3 seconds it is impossible to fly 15 m/s and get 90% overlap from 20 meters.
Map Pilot calculates the fastest speed you can fly given the altitude and along track overlap settings you have made.
If you must fly faster you can either fly higher, use less along track overlap, or use a faster SD card write speed setting.