NFS can be super fast, in a past life I had to work a lot with a large distributed system of NetApp Filers (hundreds of filers located around the globe) and they have a lot of fancy logic for doing doing locale-aware caching and clustering.

That said, all of the open source NFS implementations are either missing this stuff or you'd have to implement it yourself which would be a lot of work. NetApp Filers are crazy expensive and really annoying to administer. I'm not really surprised that the cloud NFS solutions are all expensive and slow because truly *needing* NFS is a very niche thing (like do you really need `flock(2)` to work in a distributed way).