NFS client is very slow to open files and get items properties

Hi,
I just install built in NFS Client for Ultimate version to connect to a linux server.
Mount works fine, directory exploration too but I have a very long delay on right-click on any items on NFS mapped drives and Office opening session.
Open the same file with an simple hex editor is quite instant. Transferts rate is 1Gbps from the mapped drive to local computer.
No antivirus, no firewall, just a point to point between my computer and the server.

If someone have an idea to speed up these access...
regards