Hi Tangens,
There is a way... but it only works without having sound
Within the configuration select:
display -> resolution -> full screen (set enabled)
display -> options -> multiple buffers (set enabled)
sound -> sound emulation -> no sound
Normally, WinFellow synchronizes its emulation to the sound emulation, which is running on PAL speed (50 Hz). By turning of sound, WinFellow will run at full speed. By enabling full screen in combination with multiple buffers, the flip of the two graphical is synced to the VSYNC signal.
I don't know if this is helping, but with the current implementation you must choose between synchronization or sound.
Good luck,
Worfje