The GTX 750 is actually the poorest card in the 700 range:

http://www.videocardbenchmark.net/gp...rce+GTX+750+Ti

If you look at those benchmarks, you will see that a GTX 680 does better, with the 750 10th in a list of 10 cards. It's a great value card for a reason! Nobody buys it because it isn't very good.

I suggest that you lower your resolution in both games to 720p, and turn off shadows (that is a killer for any graphics card - including a GTX Titan). Try it from there. If it is still laggy, try turning the textures down to medium.