presets are just speed hacks you can do it manually
it seems you haven't enabled speed hacks at all
I enabled some, tried different settings and got no FPS boost *shrug*. I suppose it'd help if I knew what I was doing.
The most effective solution is overclock your 750. According to my experience, The Lynnfield series CPU does not run too hot if it is just a mild OC at a speed of around 3.5Ghz, and even higher if you use a high quality aftermarket cooler.