AppKit windows that “close” but keep their NSViewController trees alive can turn into scrolling jank and quiet memory creep. The fix starts with seeing the actual owners, not guessing from heap size.

• Use Debug Memory Graph to trace strong-reference paths from an NSViewController to the NotificationCenter token, timer, or closure that’s holding it.
• Pair it with Instruments > Allocations for time-based growth; short spikes won’t always appear in a snapshot.
• Teardown where it reliably runs during close: NSWindowDelegate.windowWillClose(_:) (remove observers, cancel timers), not only in deinit.
• Prefer owned, cancelable timers like DispatchSourceTimer over repeating Timer tied to the runloop.
• Audit NSTableView/NSCollectionView adapters: closure callbacks that capture self can