Very, very, very, slow to open network share with many files

I have a Win10 PC on my network with some shared directories, the "server". The share I use most has 23,000 files in 600 folders. When I access that share from a Win 7 PC it opens pretty much instantly, but to open it from my Win 10 PC takes for ever. The green progress bar creeps across the top of the window, it can take 10, 15 minutes or more Seems like it's indexing it or something.

I changed the Win 10 PC from hard wired to wifi for direct comparison to the Win 7 laptop - made no difference.

I disabled "Large Send Offload" on the "server" and that has sped up transfer of large files, but has done nothing to speed up the initial problem. No issue with Win 7 clients, so I think it has to be a Win 10 setting?

Disabled Windows Defender and Firewall - no improvement

Switched to Linux.