Moving/copying files takes forever

System information:
Nextcloud 12.0.3 on linux server
Users data is on windows shared disk.
Moving one file 5gb in local disk from one folder to another takes about 10 min via nextcloud web interface. Doing same action locally via windows explorer it moves file instantly. Maybe someone knows there’s problem? Or where i can begin digging to find out solution.

Can it be because of two different mounts of same shared disk but two different folders?

Sincerely, D.