From my long experience building high-end NAS servers and struggling with Macs, generally using 10GigE connections:
Using SMB, the typical Mac pro can't do much better than 150/200MB/s to/from the NAS.
The very same Mac booted on Windows via Boot Camp reads/writes at 1GB/s on the same NAS.
Back to MacOS, using either NFS or AFP the Mac easily reads/writes at 1GB/s on the NAS.
The SMB implementation of MacOS is utterly broken, and has been for ages. NFS works fine generally, but some programs such as Quicktime pro and more annoyingly, the Finder sometimes have trouble with it.
Unfortunately, the fastest and most reliable option by a large margin still is AFP, using Netatalk. If you take care of cleaning regularly the CNID database, it works like a charm. I have many customers using servers with hundreds of TB of storage with AFP and it just works.
There's no SMB on my home network at all, since I don't have any Windows machines to support. For file storage/access, I use NFS which works beautifully across my Macs and Linux boxes. Speeds are appropriate for a 1Gbps link. For Time Machine, it's netatalk pointed at a HFS+ volume:
[Time Machine]
path = /mnt/backups
time machine = yes
This setup has been rock-solid for close to a decade, and persisted across different NAS hardware. Current NAS is a Buffalo Terastation minus it's crappy built-in software, plus a barebones Debian install.
They do, under the hood. (or did at one point.) the problem is it doesn't work. it's functional, but just doesn't give the level of performance needed at the top end (where wifi isn't a good enough connection).
They used to, a very long time ago, and when they did it was an outdated version. Nowadays they have a proprietary alternative that sucks.
Modern Samba is limited by the TCP stack. You can get 10gbps to work as long as your TCP stack is performant enough with very basic tuning on the server side. The client "just works".
macOS stopped shipping Samba with 10.7 Lion. Even before Samba was outdated.
Not to get political but I always thought it was a mistake to make "modern" samba GPLv3. All it did was make all these hardware vendors either stick with the older GPLv2 stuff or... I dunno what else they can do besides write their own implementation.
Samba is too much of an "infrastructure" codebase. It should have been BSD licensed. Vendors would have strong incentives to merge changes back into the mainline... none of them want to have their own wacko implementations.
Samba operating on the application layer and working the way it does means you can totally ship a computer that runs Samba with the immediate tooling around Samba also bring GPLv3 and the rest being proprietary.
Even when they did, somewhat 10+ years ago, it is still far from perfect for whatever reason. But no one cared much because we were all taught to just use AFP.
Ten years ago Apple abandoned Samba. But Samba back then was much worse than Samba today, which is of equal quality to the Windows Server stack but harder to configure.
Using SMB, the typical Mac pro can't do much better than 150/200MB/s to/from the NAS.
The very same Mac booted on Windows via Boot Camp reads/writes at 1GB/s on the same NAS.
Back to MacOS, using either NFS or AFP the Mac easily reads/writes at 1GB/s on the NAS.
The SMB implementation of MacOS is utterly broken, and has been for ages. NFS works fine generally, but some programs such as Quicktime pro and more annoyingly, the Finder sometimes have trouble with it.
Unfortunately, the fastest and most reliable option by a large margin still is AFP, using Netatalk. If you take care of cleaning regularly the CNID database, it works like a charm. I have many customers using servers with hundreds of TB of storage with AFP and it just works.