Korx got crushed. I don't know exactly what it is, but they never keep up. My guess is that they are researching their unique techs too soon. They spend the first year or so on that and don't get a chance to upgrade their infrastructure before the arms race. Being stuck with Traditional Factories and Labs in year 4 and 5 is a death sentence.
I'm not sure what the big problem with the Korx is, but they've been steady at the bottom of the pack. The idea that their unique techs are behind it might have some basis; they're the only race that's doing worse now then they did before I starting modding things. I have a couple of custom races with the Korx tech tree and they've done okay, though, so maybe it's something else.
AI 8 also doesn't like Manufacturing techs a whole lot. The Drengin started out strong, but bit off more than they could chew. Over the long haul they declined while their enemies grew. Turns out they never researched Slave Canyons - not until I made them do it near the end. That means they were stuck with Slave Pits, with a lousy 5mp each. They simply got out-produced, even when they were down to only 1 enemy.
Haven't really run into this behavior before. My Drengin on AI 8 tend to be pretty quick about researching Slave Canyons - sometimes, they get it before the arms race even starts.
AI 8 really doesn't like Extreme Colonization (Colonization category techs). By game end, the Terrans still had not researched it. The AI 8 strategy really seems to be conquer, not settle. It works, to a certain extent. The Terrans were a major power, the Iconians were leading for most of the game, and the Drengin started out strong.
Not sure what I want to do with this. Do I try to force it, or just accept it as the AI 8 way?
Personally, I'd just go with it - it's good that the AIs act in visibly different ways. Then again, it may depend on circumstances - you seem to use higher extreme planet counts then I usually do.
In other news, I've finally gotten the Arceans to pull themselves together. They'd been having issues for sometime, but they look to have been partially setup based - right now, they're middle of the road. The first run of the new Korath tree is looking good too.