From my limited (as of now) experience with Ancient Empires, I'd say it runs better than vanilla Attila, especially in messy situations. Which makes sense, because most of the assets AE uses are much inferior in quality compared to Attila.
Just look at the textures of shields, armor and (especially) helmets.
You really can't compare, which is fine though, since the mod is meant to take advantage of Attila's improved features rather than graphics.
I wouldn't mind a graphic overhaul in the future though