A big part of that smooth experience is all the progress that’s been made in the past month, on both Lemmy and Memmy.
The Memmy app only started out as a beta in TestFlight ~4 weeks ago, and was limited to 10k users. The developer has made a truly inhuman amount of progress in that time - he was (and still is) pushing updates more than once a day. It’s only been in the regular App Store for a few days now.
Additionally, the largest Lemmy instance (lemmy.world) was having stability issues with the massive influx of users. But just a few days ago they figured out what was causing the problems, and the latest version of Lemmy has those fixes.