Support rep here. Yes, the way we handle files depends on their file size - what Coel says is correct, that the cutoff is around ~5mb (I don’t think it’s actually 5mb on the dot)
anything less than that will come through from the node, and everything above will stream from the origin.
The netlify docs don’t really contain tons of infrastructure info about our CDN, but i will check in with docs team and ask if we can put this info somewhere.
In general, if something is mentioned in a Support Guides then it is safe to trust. The closest i found to mentioning this limit is in here:
i agree that we could have this better documented and I’ll see what we can do about that.
In the meantime, breaking files down into smaller sizes is the way to go. Not sure what you mean by pre-compressing - are you talking about compressing them locally and then using asset optimization to squeeze them down further or? Not sure using our asset optimization algo will help much on top of what you are already doing)