The .io infrastructure under ICB was indeed quite slow. Everything moved to Afilias (and now Donuts) many years ago though and EPP is quite performant now fortunately.

We deal with a few independent ccTLDs these days that are still horribly unreliable though. Not going to name any names but some of these are quite popular and still either don't run on EPP and/or run on an old outdated server in a local DC.