Very slow opening and saving excel files on NAS

I too have been having this problem. What makes it really strange is that it hasn't always been this way. Excel files used to work just as well as any other file type until it randomly started acting up. I've been unable to pinpoint what made it start acting this way. Also, other MS Office files work fine; only Excel files are slow to open and save on the ReadyNAS Duo. It's currently quiet a headache to copy files to a specific computer, edit the file, then put it back to make sure everything stays updated. If the OP has fixed this issue or someone else has an idea, I'd love to hear it as I'm fresh out of things to try.