Oh yeah, I see what you mean. I found a file with a bunch objects (trees from the extension) which I could easily duplicate and made a file with 375 objects, somewhat complex objects. So far (5 minutes) the progress bar still doesn't show anything, it's not telling me how long is left. So it does seem to take a while!
I do see some settings under the gear icon. It would seem you could speed it up with certain settings. But I'm not really sure what a lot of them are or mean. Oops - crash went the browser! Yikes!
Ok. I made a much simpler file, with only about 50, and much simpler objects, and it went in a couple seconds. I'll bet the number of nodes per object has a lot to do with how long it takes. Oh, or it could be the outer dimensions of the container shape have something to do with it too? Or it could be that having closed shapes is the key. My first file was all open paths.
Anyway, thanks for sharing. I hope the Issue Moini referenced will be added sooner than later.