@@ -412,9 +412,18 @@ const TreeSelect = React.forwardRef<BaseSelectRef, TreeSelectProps>((props, ref)
     // Convert to value and filled with label
     const values = displayKeys.map(key => keyEntities[key]?.node?.[mergedFieldNames.value] ?? key);
 
+    // Avoid an O(displayed values × selected values) lookup
+    const labeledValueMap = new Map<SafeKey, LabeledValueType>();
+    rawLabeledValues.forEach(item => {
+      // Match `find` by keeping the first entry when controlled values contain duplicates.
+      if (!labeledValueMap.has(item.value)) {
+        labeledValueMap.set(item.value, item);
+      }
+    });
+
     // Back fill with origin label
     const labeledValues = values.map(val => {
-      const targetItem = rawLabeledValues.find(item => item.value === val);
+      const targetItem = labeledValueMap.get(val);
       const label = labelInValue ? targetItem?.label : treeTitleRender?.(targetItem);
       return {
         value: val,
 
@@ -531,6 +531,30 @@ describe('TreeSelect.checkable', () => {
       expect(getSelectionText(container, 0)).toEqual('0-0');
     });
 
+    it('preserves labels with SHOW_ALL', () => {
+      const { container } = render(
+        <TreeSelect
+          treeCheckable
+          showCheckedStrategy={SHOW_ALL}
+          labelInValue
+          value={[
+            { value: 'parent', label: 'Custom parent' },
+            { value: 'child', label: 'Custom child' },
+          ]}
+        >
+          <TreeNode key="parent" value="parent" title="Parent">
+            <TreeNode key="child" value="child" title="Child" />
+          </TreeNode>
+        </TreeSelect>,
+      );
+
+      expect(getSelections(container)).toHaveLength(2);
+      expect([getSelectionText(container, 0), getSelectionText(container, 1)]).toEqual([
+        'Custom parent',
+        'Custom child',
+      ]);
+    });
+
     // https://github.com/ant-design/ant-design/issues/38126
     it('keep label when not in options', () => {
       const onChange = jest.fn();