A1bill, I have to say that I haven't tried doing a side-by-side comparison between the various types, but if you're noticing differences in performance, three things occur to me.
First the T-50 is a a fairly early prototype with the wrong engines - impressive as they appear to be. Second, the display may have been to show that slow-speed, high-aoa awesomeness. Third, you may be seeing some of the costs of the stealthy form - the trade-off between aerodynamics and low RCS. Most likely a bit of all three.