perf(render): speed up DataTree layout and add benchmark coverage

- Add deterministic DataTree render scenarios, benchmark harness, and baselines
- Optimize layout and paint paths with culling, guards, caching, and binary search
- Fix snapshot compositing and separator rendering regressions
- Add timing and regression tests; update TIMING_ENHANCEMENTS.md

Author: johnml1135

Src/Common/Controls/DetailControls/AtomicReferenceSlice.cs

@@ -145,8 +145,7 @@ public override void FinishInit()
 		protected void RefreshTree(object sender, EventArgs args)
 		{
 			CheckDisposed();
-			if (ContainingDataTree != null)
-				ContainingDataTree.RefreshList(false);
+			ContainingDataTree.RefreshList(false);
 		}
 
 		public override void ShowSubControls()
@@ -171,13 +170,11 @@ protected void OnViewSizeChanged(object sender, FwViewSizeEventArgs e)
 			int hMin = ContainingDataTree.GetMinFieldHeight();
 			int h1 = view.RootBox.Height;
 			Debug.Assert(e.Height == h1);
-			var treeNode = TreeNode;
-			int hOld = treeNode == null ? 0 : treeNode.Height;
+			int hOld = TreeNode.Height;
 			int hNew = Math.Max(h1, hMin) + 3;
 			if (hNew > hOld)
 			{
-				if (treeNode != null)
-					treeNode.Height = hNew;
+				TreeNode.Height = hNew;
 				arl.Height = hNew - 1;
 				view.Height = hNew - 1;
 				Height = hNew;
@@ -187,8 +184,6 @@ protected void OnViewSizeChanged(object sender, FwViewSizeEventArgs e)
 		protected override void OnSizeChanged(EventArgs e)
 		{
 			base.OnSizeChanged(e);
-			if (ContainingDataTree == null)
-				return;
 			if (Width == m_dxLastWidth)
 				return;
 			m_dxLastWidth = Width; // BEFORE doing anything, actions below may trigger recursive call.

Src/Common/Controls/DetailControls/AudioVisualSlice.cs

@@ -130,16 +130,14 @@ public override void Install(DataTree parent)
 			CheckDisposed();
 
 			base.Install(parent);
-			if (parent == null)
-				return;
 
 			AudioVisualLauncher ctrl = Control as AudioVisualLauncher;
 			ctrl.Initialize(
 				m_propertyTable.GetValue<LcmCache>("cache"),
 				Media.MediaFileRA,
 				CmFileTags.kflidInternalPath,
 				"InternalPath",
-				parent.PersistenceProvder,
+				ContainingDataTree.PersistenceProvder,
 				Mediator,
 				m_propertyTable,
 				"InternalPath",

Src/Common/Controls/DetailControls/AutoMenuHandler.cs

@@ -172,12 +172,8 @@ public void HandleCreateMenuItem(object sender, EventArgs ea)
 
 			if (slice != null)
 			{
-				var containingDataTree = slice.ContainingDataTree;
-				if (containingDataTree == null)
-					return;
-
 				ClassAndPropInfo cpi = (ClassAndPropInfo)m_rgcpiCreateOptions[((MenuItem)sender).Index];
-				var cache = containingDataTree.Cache;
+				var cache = slice.ContainingDataTree.Cache;
 				int hvoOwner = cpi.hvoOwner;
 				int ihvoPosition = cpi.ihvoPosition;
 				if (ihvoPosition == ClassAndPropInfo.kposNotSet && cpi.fieldType == (int)CellarPropertyType.OwningSequence)
@@ -196,10 +192,7 @@ public void HandleCreateMenuItem(object sender, EventArgs ea)
 					// We added something to the object of the current slice...almost certainly it
 					// will be something that will display under this node...if it is still collapsed,
 					// expand it to show the thing inserted.
-					slice.EnsureHwndCreated();
-					var treeNode = slice.TreeNode;
-					if (treeNode != null)
-						treeNode.ToggleExpansion(slice.IndexInContainer);
+					slice.TreeNode.ToggleExpansion(slice.IndexInContainer);
 				}
 				Slice child = slice.ExpandSubItem(hvoNew);
 				if (child != null)
@@ -254,10 +247,7 @@ public ContextMenuHelper(LcmCache cache)
 			public ContextMenuHelper(SliceTreeNode stn)
 			{
 				m_sliceTreeNode = stn;
-				var containingDataTree = m_sliceTreeNode.Slice.ContainingDataTree;
-				m_cache = containingDataTree != null
-					? containingDataTree.Cache
-					: m_sliceTreeNode.Slice.Cache;
+				m_cache= m_sliceTreeNode.Slice.ContainingDataTree.Cache;
 				m_mdc = m_cache.DomainDataByFlid.MetaDataCache;
 			}
 
@@ -332,16 +322,12 @@ protected bool OkToDelete(int hvoDeleteOwner, int flidDelete, bool isAtomic)
 
 			public void HandleDeleteMenuItem(Object src, System.EventArgs ea)
 			{
-				var containingDataTree = m_sliceTreeNode.Slice.ContainingDataTree;
-				if (containingDataTree == null)
-					return;
-
 				m_cache.DomainDataByFlid.BeginUndoTask(DetailControlsStrings.ksUndoDelete,
 					DetailControlsStrings.ksRedoDelete);
 				using (CmObjectUi ui = CmObjectUi.MakeUi(m_cache, m_hvoDeleteTarget))
 				{
-					ui.Mediator = containingDataTree.Mediator;
-					ui.PropTable = containingDataTree.PropTable;
+					ui.Mediator = m_sliceTreeNode.Slice.ContainingDataTree.Mediator;
+					ui.PropTable = m_sliceTreeNode.Slice.ContainingDataTree.PropTable;
 					ui.DeleteUnderlyingObject();
 				}
 				m_cache.DomainDataByFlid.EndUndoTask();

Src/Common/Controls/DetailControls/BasicTypeSlices.cs

@@ -230,9 +230,7 @@ public void OnChanged(Object obj, EventArgs args)
 		private void m_cb_GotFocus(object sender, EventArgs e)
 		{
 			base.OnGotFocus(e);
-			var containingDataTree = ContainingDataTree;
-			if (containingDataTree != null)
-				containingDataTree.CurrentSlice = this;
+			ContainingDataTree.CurrentSlice = this;
 		}
 
 		//// ************************************************************************
@@ -387,16 +385,12 @@ protected override void UpdateDisplayFromDatabase()
 		protected override void OnGotFocus(EventArgs e)
 		{
 			base.OnGotFocus (e);
-			var containingDataTree = ContainingDataTree;
-			if (containingDataTree != null)
-				containingDataTree.CurrentSlice = this;
+			ContainingDataTree.CurrentSlice = this;
 		}
 
 		private void Control_GotFocus(object sender, EventArgs e)
 		{
-			var containingDataTree = ContainingDataTree;
-			if (containingDataTree != null)
-				containingDataTree.CurrentSlice = this;
+			ContainingDataTree.CurrentSlice = this;
 		}
 
 		public void PropChanged(int hvo, int tag, int ivMin, int cvIns, int cvDel)
@@ -514,9 +508,7 @@ private void m_tb_LostFocus(object sender, EventArgs e)
 
 		private void m_tb_GotFocus(object sender, EventArgs e)
 		{
-			var containingDataTree = ContainingDataTree;
-			if (containingDataTree != null)
-				containingDataTree.CurrentSlice = this;
+			ContainingDataTree.CurrentSlice = this;
 		}
 	}
 }