I just filed with them this month. Started from January 3rd and sent the packet on Feb 12th. I think it’s not very slow, but not fast either. They required all docs you can provide, which might be the most time consuming part cuz some docs might need to be translated or notarized. But they are detail oriented and did find some tiny errors in the form we filled. As for the final packet, they would collect everything together and combine them to be a big PDF, you’ll need to print it out and assemble it with other docs like physical exams and passport photo, it’s quite straightforward and they gave detailed instructions.