To speed up SMB file browsing, you can prevent macOS from reading .DS_Store files on SMB shares. This makes the Finder use only basic information to immediately display each folder's contents in alphanumeric order. Use this Terminal command:
defaults write com.apple.desktopservices DSDontWriteNetworkStores -bool TRUE
Then log out of your macOS account and log back in.
To reenable sorting, use this command:
defaults write com.apple.desktopservices DSDontWriteNetworkStores -bool FALSE