Yes, a progress bar would be a great solution. Just spinner does not work, because it may also be a feeling that hung
I totally agree! That feature is a MUST!
I thought after customer hit "finish and add to cart" button, he should see a blank page with spinner or progress bar and warning text "your order/card/design is loading, please do not leave or refresh this page until it's finished"
I also think we should get a "Please wait..." or something when the whole product page/editor is loading. Right now it seems like the user is just staring at a blank page until the editor comes up, and it can take quite a while.
Included in V3.9.2