Thanks, for the info.
I'm glad that it works adequate without resorting to disabling anything now. Although I am only using guest access fairly simple shares, so I probably won't need the above attributes.
Maybe readonly, but I have that set to shares when needed.
Still odd that many systems and users seems unaffected, storing files and folders is a very common use for a NAS after all.
The parameters I mentioned before are 'global' parameters. This means all your shares have them or none of your shares have them. Samba only reads the user.DOSATTRIB extended attribute of files in the folder where you are located as well as the current path in the file tree. Less files in folder or simpler file tree eliminates the problem in many cases. More ARC also improves ZFS's ability to cache the extended attributes.
That being said, there are many issues that combine together to make browsing slow. DOS modes are only part of the equation (in some cases it may be the primary cause). Using SMB2 instead of SMB1 can improve performance (SMB2 is
much more efficient than SMB1 - if I remember correctly smbclient defaults to SMB1). Disabling thumbnail generation can help. Changing antivirus solution can help.
If you're using some sort of linux box to watch movies over CIFS / browse your file tree, you can modify your client's (not your FreeNAS server) smb.conf file by adding the following global parameter:
client max protocol = SMB3
This requires that your client have a minimum of samba 4.1.0.
You may experience some bugs as unix extensions and a few other samba features are not presently supported under smbclient.