Karnak, there you have a good example. Your mossie is faster than 109G6 and 109F, but they'll beat you over'n over due their acceleration. Speed is a secondary factor if there is no surprise factor to do real boom&zoom attacks. Of course you will have the chance to flee by speed, but only if you outaccelerate quick enough your enemy to get a real speed advantage and a substantial separation, and I know only one plane able to do this: La7.
The second key factor, IMO, is control at hi speed (hi speed is not extreme speed).
Any of our planes is suitable to be a hi speed fighter, even a 109F. Climb enough, do a sallow dive and keep fast all the time. The problem with the so-called slow fighters is that they are used mainly in a TnB way, burning all their speed doing flat turns. Neither so-called fast planes nor slow ones can sustain any speed advantage used only this way. If found a lot of good spit drivers having a slight alt advantage over my D9, and keeping that advantage on alt or speed all the time, no way to catch them. Of course, these pilots know how to use a spit instead trying to turn in a dime and pointing their hispanos towards my 190.