That was quick.
One day after exchanging my iPhone X for a new one that did not fix the iPhone X Suica problem it was back to testing beta software. Again. I sprinted through my golden circuit of error prone JR East station gates and the new iPhone X Apple Pay Suica left a sweet trail of flickering red transit gate errors. It was bizarrely comforting.
iOS 11.4 is already beta 2. I doubt there will be any improvement in the official release but I will continue testing and post any developments.
iPhone X Apple Pay Suica performance has become an endless joke without a punchline. At this rate I doubt we will see any Suica performance tweaks in remaining iOS 11 releases. iOS 12 will probably be the best hope for that.