[bluSCALE4]

I'd be interested in knowing if he was multitasking and using a lot of memory. I know wedding photos are usually something you feel rushed to upload so maybe this issue can be made worse depending on system resource availability.

[inanutshellus]

yeah copying can take a loooooooong time and so you multitask.

maybe the randomness is based on the other apps he's using at the same time.