I'm also curious if there's practical limit to the number of images that can be contained within one album. The album in question has just over eleven thousand images (5.9gb). The scratch remake took ten minutes which I thought was impressive and the upload, (thanks to my stingy hosting service,) took sixty-six minutes but I was only able to get 12mbs during the upload.
There are users who have
much larger projects than that. There's almost no inherent limit within jAlbum.
But there's nothing jAlbum can about your upload speed. And in fact, many ISP's offer stunning download speeds, but they're not symmetrical. My host is now up to 400mpbs download, but is still stuck at 11mbps upload speed. Fiber would offer upload at the same speed as download.
Install this app, and do some testing (with nothing else running, of course):
https://www.speedtest.net/apps