Well the closest comparable game, Mount and Blade has a speed scale that starts slow, for the cheapest possible units, then starts giving both fast and slow options from medium quality upwards. That way the default speed for cheap armies (the pirate equivalent, aka what-a-new-player-fights) is slow and predictable.
Fast fleets ("cavalry") maybe shouldn't be the default, but rather a choice when you start upgrading from the default.
On another note, MnB also has extremely crappy, extremely cheap chaff units, something I always thought was missing from Starsector. Thanks to the new salvage system and D-mods, that's been changed.