Why does a large Canvas with a WebGL context take up a lot of memory?

Question

Canvas

Example:

var c = document.createElement('canvas');
  var ctx = c.getContext('webgl');
  c.width = c.height = 4096;

I just got the context and resized the canvas, no more actions were taken, and the GPU memory (with canvas sides 4096) takes almost 400 mb. Why is that? Where is the memory allocated?

Answer 1

WebGL has a depth buffer, anti-aliasing, and an alpha channel enabled by default, so it eats up a lot of memory.
Source