Ultra isn't ment for the gtx 750 ti and is more for the gtx 980ti and titanX, the standard version is more geared toward the gtx 750 or there about cards and really 25fps with ultra is quite good. We have gtx 980s and depending on the saved world we get from around 40fps to about 65-70 with continuum high. To be honest there isn't that much more room for optimization and really at most we would only see a 5fps increase maybe 10at Max
A 5-10 FPS increase would be amazing, though. It would definitely provide a more stable framerate.