Ok i understood your limitation that is interesting to point them out thank you
So i played the web version, i saw afterwards the message pointing problems os my bad on that
To be honest i am using Godot and i was used to have problem on HTML export so what you mentionned really make sense for me xD
But i find to solve the performence problem on HTML export with some of those things : Using the Godot Gdscript version isntead the Mono one for C#, Exporting in compatibility mode instead of forward +, capping the max number of FPS, using CPUParticules instead of GPUParticules, etc. I'm using Godot 4.2.2, which versions did you used ?
Also look forward the Godot 4.3 version that will soon be launched and it seems like they fixed issues with HTML export : https://godotengine.org/article/progress-report-web-export-in-4-3/