I looked at 9p as a NFS/SMB replacement some time ago for a project, and benchmarks seems scarce. I did find this[1] set of benchmarks but it's from 2005.

I also found this[2] from 2016 which points out some performance barriers, and it doesn't sound like an easy fix without some new extensions.

However there's also this[3] post from 2022 about some patches suggesting a 10x improvement in Linux 9p performance.

Would be interesting to see how things are these days.

[1]: https://www.usenix.org/legacy/events/usenix05/tech/freenix/f...

[2]: https://github.com/Harvey-OS/harvey/issues/18

[3]: https://www.phoronix.com/news/Linux-9p-10x-Performance