How do I speed up backup?

[grmgroup]

I had to reformat my HD. I installed my backup file (made a copy after last back up knowing I was reformatting). But now it take 20 minutes to do a backup even if I haven't edited one file. I back up to DVD on a dual G5, mac)S 10.4.11 running reto 6.1.126. I only back up my work folder which is a networked external drive. In the past, if I didn't do any work on a file, the backup would scan and quit in a few minutes. Now it takes 20 minutes just to scan the work folder whether I edit or create one file or 400. I currently have "all files but cache files". I never back up the HD itself or any other folder except my work folder. There are 3-5 years of legacy jobs. I also copy to an external HD once a month for safeskeeping. How do I speed up back up.

 

Again, even if I just completed a back five minutes ago, if I do another backup I wait at least 20 minutes for a scan whereas before it would take a few moments.