Not exactly sure what “streaming” text is, but serial terminal software has been handling incremental text rendering and updating for decades, without performance struggles.
By "streaming" text, I mean a formatted text stream that has to be parsed, formatted, and appended on the fly - basically how every model/AI chat works now. And this is where `NSTextView` becomes tricky. It forces an interesting architectural choice: either go deeper into AppKit with `NSCollectionView`, custom cells, manual layout, etc., or fight the whole SwiftUI model by embedding something like `NSTextView` inside `LazyVStack` / SwiftUI views & then dealing with all the integration problems.
So I am not saying Cocoa / AppKit was always bad, or that `NSTextView` is useless. I am saying that for modern chat-style UI with incrementally rendered formatted text, it does not compose well with the rest of the modern Apple stack.