The speed problem for me is not so much as how fast they walk/run but how fast they kill. The cavalry charges in particular are ridiculous but even the infantry charges look like they kill too much. Even the melee when it is supposed to be a long meat grinding thing is resolved too quickly. I charged a 30+ (already suffered a few casualties) sacred band into 100+ hastati and princeps units and they kill more than 50% in 2-3 seconds when charged at the back and around 33% when charged at the front. It's also way too easy to disengage and charge again. That part is actually fine if not for the damage charges do.

I played a game controlling the Sacred Band Cavalry almost all the time and I had 10:1 kill ratios with all 3 of them. They had more than 200 kills each and one had almost 400.