All I have is my own experience. In my current app, my views are 100% SwiftUI. One of them uses a SwiftUI List which typically has hundreds of thousands of items, each with title, subtitle, duration, cover art, etc. I expect it would still be butter-smooth at 1M items.
Was my initial naive implementation as performant? No. My point is that optimization still matters in SwiftUI, and that optimization looks quite a bit different in SwiftUI than it does in AppKit/UIKit.
Is that an iOS app? Because List on macOS still has a lot of performance issues.
This guy run a benchmark vs. AppKit and SwiftUI is still slow in macOS26
https://github.com/lemonmojo/swiftui-hierarchical-list-perfo...
If you've used UIKit to any large degree, how bad SwiftUI is, almost a decade later, continuously punches you in the face. About 20% more time to write initially, for 90% less bugs and potholes, and I've tested this with iOS devs who never used UIKit before too. Now with AI, there is even less of an excuse IMO.
Leave SwiftUI to the settings pages. The gulf between AppKit and SwiftUI in macos desktop I'm not as sure about.