Apple is doing its best tweak performance in their Samba stack, and sometimes, it might turn into a disadvantage for non Apple Samba servers.

Source: Apple

Your Mac determines how each window and its contents should appear by collecting file information such as labels, tags, and other forms of metadata.
In macOS Sierra 10.12 and earlier, your Mac gathers all metadata for the files in a folder, compares it to the folder's .DS_Store file, and then displays the folder's contents. In macOS High Sierra 10.13 and later, this behavior is changed slightly: If a folder is sorted alphanumerically, the contents are displayed immediately, then the Finder collects and compares the rest of the folder's metadata.
You can adjust macOS High Sierra 10.13 and later to make browsing faster on network shares, or to force the Finder to gather all available metadata before showing folder contents.

To get a handle on that slow performance, you can tell your macOS to not read the ".DS_Store" files on the SMB shares. Having this setting applied, it instructs the Finder to display the basic information immediately for each folder in alphanumeric order.

Use this Terminal command as the logged-in user. Typed correctly, there won't be any output.

defaults write DSDontWriteNetworkStores -bool TRUE

Then log out of your macOS account and log back in.

To re-enable sorting, use this command:

defaults write DSDontWriteNetworkStores -bool FALSE

To check the current value of the DSDontWriteNetworkStores and determine if it's off or on use this command:

defaults read DSDontWriteNetworkStores

Where 1 means it will NOT look for the .DS_Store files and 0 it will.