If you saw two frame time graphs for two different GPUs, that says a lot less about how they perform relative to each other than comparing the average frame rate that those GPUs achieved in a game.

Take a look at this frame-time graph. That doesn't look so bad, does it? A little spiky at times, but overall the frame-rate hovers around 50 FPS, which is eminently playable.

As you can see on the frame time graph, we have an uneven frame cadence of 16, 50, and 33ms, causing judder which feels worse than a 38-45fps range, as at least here frames are closer together and ...