IIRC, someone tested out the Spit V and it is basically the same speed as the Spit IX up to 10k I want to say. After that it starts falling off.
Kweassa... any plane that doesn't go 360+ on the deck fits into my "slow" category.
And since I'm using the same criteria the MA uses... you've got ~5 choices for "fast" aircraft (Tiffie, D-9, G-10, P-51, El gay), and the rest are "slow" aircraft.
The "slow" aircraft are divided into "slow, but manueverable" aircraft, and "useless" aircraft. The Spits and Niki go into the first category, everything else goes into the second.