Using Outlook for iOS in business environments for email and scheduling
No, there is no information in that site. It never lists too. In this build, yes its performance improvements, but then there are features which I believe are new to 4.23, like ability to delete S/MIME Certificates and so on.. In test flight we do get multiple updates for 4.23 - different builds. I have never seen a different note than what you see which says "Performance improvements" but definitely have seen newer features come thru.
Always the Test Flight gets the features ahead as its always a build or two ahead of the Insiders.. But I have never been able to find the release notes.