[Samba] Weird (slow) performance, querying a large 0-byte tree with lots of xattrs (ZFS over smbd)

[pb+samba at arkthis.com]

Hi everyone :)

I'm working with medium-to-large scale digitial collections in the GLAM 
(Galleries Libraries Archives Museums) domain. I'm a sysadmin, and i'm 
using xattrs increasingly to support my work handling meta+data :D

I've created thin-copy trees of data, annotated by copy exiftool JSON 
output to xattrs key/value. Each file has 0-byte (as the source payload 
data is not copied).

This works great for search/browse and other things.
So I have these "metadata filesystem trees" I'm working with.

BUT:
**When I index such a tree over Samba, I get a terrible performance and 
the CPU spikes to 100% on one core.**

For filesystem properties only access (from ZFS on Proxmox PVE 9.1, 
Debian 13)


I don't see anything in the logfiles.
And zpool has a few KBs of iostats.

I'm grateful for any hints debugging this.

Thank you :)
Peter


Additional information:
Running the index on an example tree locally (on the fileserver's ZFS), 
takes ~0.2 seconds, whereas doing the same on a client machine over smbd 
mount takes 14 seconds (GBit LAN). TAR of that tree has ~1.9 MB, so 14s 
is long IMO?