Tree::link optimization possibility

Enable option to omit duplicity checking when linking wide trees

Author: dakujem

src/Tree.php

@@ -32,6 +32,7 @@ public static function link(
         MovableNodeContract $node,
         MovableNodeContract $parent,
         string|int|null $key = null,
+        bool $preventDuplicateLinking = true,
     ): ?MovableNodeContract {
         $currentParent = $node->parent();
 
@@ -47,7 +48,7 @@ public static function link(
         }
 
         // Create the parent-to-child link.
-        self::adoptChild($parent, $node, $key);
+        self::adoptChild($parent, $node, $key, $preventDuplicateLinking);
 
         // If a parent was unlinked during the process, return it.
         return $originalParent ?? null;
@@ -163,9 +164,13 @@ public static function reindexTree(
     private static function adoptChild(
         MovableNodeContract $parent,
         MovableNodeContract $child,
-        string|int|null $key = null
+        string|int|null $key,
+        bool $preventDuplicateLinking,
     ): void {
-        $existing = $parent->childKey($child);
+        // Note:
+        // The duplicate adding prevention is very slow for nodes with many siblings due to the child node lookup
+        // (done by the `childKey` method), if not optimized internally.
+        $existing = $preventDuplicateLinking ? $parent->childKey($child) : null;
         if (
             null !== $existing &&
             $parent->child($existing) === $child &&