If a folder has many items then there is a delay when you first click on folder. But after that it is fast because contents has been cached/scanned.
Is there a script command that will cache a folder? Then I can put a list of large folders I always open inside script. I'd rather have a long delay at dopus startup, than many small delays each time I open a folder.
A startup script could enumerate the folders you want cached in the background. But note the caching is performed by the file system, not Opus, so there's no guarantee the folder would stay cached indefinitely.
There is no general folder cache in Opus. We cache FTP and archives, but ordinary folders are left to the file system to cache (which it does a perfectly good job of).