I seem to be getting better results out of the cmd window I have selected by about 1mh per card. I've split 2 750ti per .bat file and I get roughly 22.5 mh out of the non-active window and about 24.5 mh out of the active window. If I select the other one, the performance flip flops.
This is on win 8.1 x64

(what does mean "non active"/"active" windows) ?
which ever window i have selected would be the 'active' window. I've got 3 total running but only one can be the actively selected window. In total i've got 4 750 tis and a 660 gtx, so i'm running 2 instances of ccminer35 and one of ccminer30.
I can combine them all and I get roughly 55mh but I left that on over night and I crashed at some point in the middle of the night so I decided to split them up this morning.
Maybe it fixes the problem.