Slow Smart Update to encrypted sparse image
 

I created an encrypted sparse disk image from the shell using hdiutil and then have SD backing up my disk to it. It seems to be a whole lot slower Smart Updating the disk (3.33MB/s VS. 100+MB/s previously) though than it was before when I just backing up directly to my USB hard disk.

Is there reason why it's so much slower?

Sure. You've added a number of levels of indirection, including encrypting, and this is likely the first copy, so it's going to be copying a lot more. (A full backup isn't going to go at 100MB/s to USB the first time through...)

Actually, my fault. I didn't notice that I didn't have Smart Update turned on and it was completely erasing my encrypted sparse image and then backing it up. It's much faster now. Thanks for the quick reply!

You bet: glad you're all set.