Resources for Shader Optimization?

I’ve recently implemented (copied from shadertoy) a shader that creates a cool fog effect but it runs quite poorly. At 1920x1080 it gets my 3080 up to 50% load and at 1440p it can barely keep up! Surely there are some optimizations here but I don’t know the first thing about HLSL performance.

Does anyone know any good resources for tuning up a pixel shader?