Very slow to backup large files that have minimal changes

I'm currently trialling QRecall. I work with several virtual machines that need backing up often (every hour, ideally).

QRecall correctly detects changes to my VM's, and only backs up the changes. However, it takes nearly an hour to work through a ~80GB virtual hard disk. In effect, it seems to be reading through the entire file in the Backup archive to check for the changed blocks, before writing only the changes (the little pop-up notification window shows the file as being processed, with 99% duplication).

I have trialled CrashPlan, which also detects the changes and only backs up those changes. It does this in under 10 minutes.

Is it possible to optimise this in QRecall (by changing a setting) or are there any plans to speed this up in a future version?

Darrell,

QRecall 1.2—currently in beta—has dramatically improved the speed with which large amounts of data are recaptured. There are also upcoming performance improvements that address this specific issue that have yet to be released.

To participate in the beta program visit the QRecall download page, and then download and install the latest beta version of QRecall.