There are tons of videos and posts over at XDA that addresses the 30fps cap and the responsiveness issues. A lot of the evidence that these two problems are some how related. Meaning they both can be fixed.
You can believe what ever you want. But responsiveness, is how fast the phone deals with input, that would be the refresh rate of the screen.
Frames per second would be how be distance/time. To have lag, you have to have motion.
If the refresh rate was 1 per second, then every second the screen would report 1 input per second, which would be displayed at 30fps. It would talke 1/30th of a second to display that 1 input. IF the refresh rate where 85, then every second the screen updates itself 85 times. If there was 85 inputs in the second, then only 30 of them would be draw, the rest would be dropped, the dropped frames would be displayed as blur, not lag. Because it is about 20 frames per second that the human eye can make out individual frames.
Frames per second just tell how many frames per distance. They are related to each other in the fact that the fps has to wait for the refresh rate to tell it what to draw, where java always has some lagginess to it. But it ends there.
After the input control refreshes the screen it sends a signal to the video card to tell it to create the frame need to update the input.
If the input is sent to low, the refresh rate is set too low. If that happens, then user will notice the screen is going really slow or lag.
If the input refresh rate is increased, then it falls to fps second to keep up which will always be 3/25th of the inch behind for 1/30th of a second.
But to get the lag we see with the evo, the refresh rate or fps would have to drop to less then 10 fps, which is not what we are talking about.
You are the one that is taking a correlation for causation.
You are saying that the evo is capped at 30fps, so everything that is laggy about the htc evo has to be related to the cap.
And it is not.