animation from tutorial lags sometimes

[duysqubix]

when i run final code of this part of tutorial animation lags in places

video

cuted.1.1.mov

which led me to think that this behavior would also be in the game that I want to make
so I chose to use other game engine

until I found #304 and ran the command: go get -u -tags=gles3 github.com/go-gl/glfw/v3.3/glfw
after that, the problem is solved and the animation is always smooth
it turns out it was because I have apple arm cpu

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i think it is important to mention that problem and command to solve it in tutorial or other documentation
so that some people don't get wrong impression about the engine when they go through tutorial

Original issue: faiface/pixel#310