Hello,
I've unchecked the option in preferences (after enabling it via the checkbox), applied, tried restarting dopus and rebooting, but dopus continues to automatically provide folder sizes. The checkbox is not ticked.
This is a little irritating once on the road and it increases battery drain.
Maybe some individual folder settings override your general setting. You can check that by hovering over the format lock symbol at the bottom right. It lists all applying folder formats, which
most likely are responsible for the automatic folder sizes calculation. You can then turn them off individually.
The Folder Options setting allows you to override the global setting for certain special folders (e.g. ones you know have shallow sub-directories and that you often need to see the sizes of). But by default none of the folder options should be configured to override the default, so this must be something you turned on yourself in the past (unless I'm mistaken).
Not sure what Greg's post-doctorate subject has to do with anything (especially as he didn't write/design the thing in question).