It does that once, and it does it to prevent having to ship an image or base64 encoded string to create a noise effect. It's a balancing act between a bigger library and CPU usage. It takes the CPU 15 milliseconds (it's more than I expected, but it's on page load). Good to know that putImageData is faster, will look into that.

What is most likely causing the chopiness is that it's animating background gradients. There is a lot of room for improvement there, instead of animating the background gradient we could transform a layer instead.

Anyway, PR's are always welcome.