It's still a little buggy, isn't it? Sometimes I can jump two blocks high, sometimes I can't. I tested it a little:
It seems to depend on VSync and the resolution. With VSync off and at a lower resolution the jumping works correctly; with high resolution I can sometimes stand on walls or even glitch through blocks. It's probably partly because my 2006 laptop is pretty weak, but it's never affected the correct working of basic movement so far.
Hey,
What happens is that most games nowadays do their computations based on a timestep that's tied directly to framerate. Here's a good thread about this. The tl;dr is that lower framerates don't just mean choppier visuals, but also choppier calculations. This can affect everything from physics to input. That's why games that run at 60fps invariably feel more responsive than at 30fps. With a lower resolution you get a higher framerate, meaning more accurate calculations, and thus more accurate movement.
