I've installed Smush Pro and it set to work on over 200

I've installed Smush Pro and it set to work on over 200 images already in the Media library, but now it seems to be hanging at 129 of 218 images. It's been stuck there for a while...10 or 15 minutes, probably more. Is this normal? How long should I wait before bailing out? And CAN I bail out at this point? If I do close the page, will the plugin pick up where it left off when I go back to it?