I think what makes FUSE/FSKit great here is that agents usually only need to see the file metadata + read a handful of actual files, rather than some applications needing read many things. If you're doing huge rewrites, this is a problem, but most tasks are usually somewhat small. Definitely is a problem that I've ran into though, we do cache aggressively to try to solve some of this, but it'll never be as fast as reading/writing directly to disk. We have benchmarks [1] if you want to take a look at how we're testing some of the performance there.