I was able to prompt ChatGPT Codex to fully rewrite the render logic using GLSL (without me having to edit it at all). After the first 2 prompts, it was almost fully functional. It took 6 prompts in all to get a full rewrite in GLSL. I have never worked on GLSL code (and was kind of dreading this rewrite), so this was a HUGE accelerant for me. Shout out to OpenAI for an awesome product!
One last thought: this almost felt like a compiler, where I write in a higher-level language (vanilla JS), and have the AI compile it to GLSL for me.