Earlier quoted context omitted.
So what do you suggest I should change? Thanks in advance.
Well in CSS you can't do anything about it, that's just how the browser works. If you'd be doing WebGL you can do some things like using square power of two textures and enabling mipmapping and if available anisotropic filtering. You can also do things like using signed distance field fonts or draw fonts by rasterizing (in the fragment shader) the bezier curves, which can be made to nicely anti-alias (using standard…
So, ideally, browsers would be doing this themselves, after applying the transform to any non-text in the texture, and then compositing with the combined texture?