Incremental backup of large amount of files is very slow

Hi all,

Is there a way to speed up incremental backups of directories with large 
amounts of files?

Backing up my mail storage (1 file per email) takes a very long time, I'm not 
sure what it's doing, but as it takes a long time before it actually starts 
writing the backupfile, I feel it's checking the content of every file against 
the catalogue.

If this is the case, is there a way to have dar only compare the name (if it 
exists) and filesize? I am willing to risk minor losses for most of the 
incrementals. I would be doing regular "masters" where this option would not 
be used.

Many thanks,

Joost