Readme

Author: lemonmojo

README.md

@@ -1 +1,18 @@
-# swiftui-hierarchical-list-performance
+# SwiftUI Hierarchical List Performance
+
+This is a demo project that highlights performance issues with hierarchical SwiftUI lists.
+
+There are three main problems:
+
+1. Rendering of the list is slow if there are many items. (Just start the app and wait for the list to be rendered.)
+2. Changing the selected item is very slow. (Tap/Click an item and wait for the selection to change.)
+3. Updating the list is slow. (Press the "Shuffle" button.)
+
+On an iPhone 13 Pro, it takes 6 seconds from tapping the app icon to the list being rendered. This was timed with a release build.
+Once the list has been rendered, it takes 8 seconds for the selection to change when tapping an item.
+Tapping the "Shuffle" button results in a 2 seconds delay before the updated list is rendered.
+
+All three problems are much more pronounced on macOS (tested on a Mac Studio M2) where it even takes minutes(!) for the app to become responsive.
+
+Instruments shows that 99% of the CPU time is spent somewhere deep inside SwiftUI.
+Various attempts have been made to fix the problems (as documented in the code) but none of them have been successful.

SwiftUIHierarchicalListPerformance.xcodeproj/project.pbxproj

@@ -11,6 +11,7 @@
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@@ -36,6 +38,7 @@
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