Much of the time we know that changes only occurred in a portion of the tree, but create-filelist will always stat the entire file tree to completely regenerate the list. It would be a very useful performance improvement to change this.

• Accept multiple copies of a new option to specify the prefix.
• Also need the old file list.
• Can copy anything that doesn't match one of the prefixs straight to the output without having to stat anything.

Things to think about:

• It's kind of an unpleasant hack, but....
• Ordering has never been important so cramming the old stuff at the end (or the beginning) doesn't matter.
• Is it important to also make sure that parent dirs are stat'ed up the tree?