This game was made in a hurry because at the time Relic was under a lot of pressure to make something happen. I am a developer myself and i can tell you that software as complex as COH2 made in a hurry it's a recipe for failure.
Most probably at this time the code is too complex and risky to make changes so nobody wants to touch some parts of it( i know i wouldn't). Performance software requires to know the code inside out and most probably some of the original developers are not even working there anymore.
To be honest, as a developer, considering how diverse this game is ( so many units and possible interactions), i am surprised that the game is not crashing more often or having more weird bugs.
So good job on the programming part Relic, not the balance part
