

You can always write native apps or use rust. I don’t recommend doing that unless perfectionism/being esoteric/learning is more important to you than just making the webapp.
The main issue with fb/TikTok is the 9 billion trackers and ads. So step 1. Don’t do that.
Svelte/SolidJS are smaller/faster than react/ vue. React has the most tutorials, but I think vue is the easiest to learn.
Next, while working on your app (probably all of those use “vite” instead of web pack by now) meticulously watch your build size. Avoid installing giant dependencies if you can. If you have lots of options, pick libraries that are tree-shake-able. rollup-plugin-visualizer will help you visualize which Javascript file(s)/ dependencies are big. You’d be see surprised how many webapps that is basically 10kb of functionality ends up being 1MB of Javascript.
If your webapp is small you probably don’t need to think too much more about this, but you could probably ask others to critique your code later.
IDK I’d assume anything uploaded more than 10 years ago needs to be re-encoded (but you should learn more about the old and new encodings before generalizing that blindly).
I’ve also had success removing embedded language audio tracks from a file that had 5+ languages from the original Blu-ray. Each language was over 1GB/per movie for a specific offending collection.