Just to add to the excellent advice being given above, I wouldn't count on poor performance on Speeds 3 and 4 as a valuable metric. While I agree that the GPU is your weak spot, this can happen on stronger hardware as well and is often a symptom of the game engine tripping over itself just as easily as anything else. It is possible that reducing the load (the EPs) in this case may not make a dramatic difference.
Personally I wouldn't attempt my own expansive play style on a 930M with Pets and Seasons as part of the mix. But if you can get and maintain acceptable game performance on all EPs except for when running the game at higher speeds, then you are already ahead of the curve there.
