[rdiff-backup-users] Is there an option to avoid comparing unchanged directories?

[Karjala]

Hi

Is there an option on rdiff-backup to to make it not look into 
directories that haven't been changed since the last backup?

The "last-modified" date on a directory shows when there has been any 
change in a file inside that directory or any of its subdirectories. So 
it makes sense that somebody might want to save time and CPU and HD time 
by asking rdiff-backup to ignore directories that haven't been changed 
since the last backup.

Is there such an option on rdiff-backup?

Thx