diff --git a/core/string/string_builder.cpp b/core/string/string_builder.cpp
index 4f74a2e42dc7..d08bcdb9d481 100644
--- a/core/string/string_builder.cpp
+++ b/core/string/string_builder.cpp
@@ -56,24 +56,33 @@ StringBuilder &StringBuilder::append(const char *p_cstring) {
 	return *this;
 }
 
+void StringBuilder::clear() {
+	string_length = 0;
+	strings.clear();
+	c_strings.clear();
+	appended_strings.clear();
+}
+
 String StringBuilder::as_string() const {
 	if (string_length == 0) {
 		return "";
 	}
 
-	char32_t *buffer = memnew_arr(char32_t, string_length);
+	String buffer;
+	buffer.resize(string_length + 1);
+	char32_t *buffer_ptr = buffer.ptrw();
 
 	int current_position = 0;
 
 	int godot_string_elem = 0;
 	int c_string_elem = 0;
 
-	for (int i = 0; i < appended_strings.size(); i++) {
+	for (uint32_t i = 0; i < appended_strings.size(); i++) {
 		if (appended_strings[i] == -1) {
 			// Godot string
 			const String &s = strings[godot_string_elem];
 
-			memcpy(buffer + current_position, s.ptr(), s.length() * sizeof(char32_t));
+			memcpy(buffer_ptr + current_position, s.ptr(), s.length() * sizeof(char32_t));
 
 			current_position += s.length();
 
@@ -82,7 +91,7 @@ String StringBuilder::as_string() const {
 			const char *s = c_strings[c_string_elem];
 
 			for (int32_t j = 0; j < appended_strings[i]; j++) {
-				buffer[current_position + j] = s[j];
+				buffer_ptr[current_position + j] = s[j];
 			}
 
 			current_position += appended_strings[i];
@@ -91,9 +100,7 @@ String StringBuilder::as_string() const {
 		}
 	}
 
-	String final_string = String(buffer, string_length);
-
-	memdelete_arr(buffer);
+	buffer_ptr[current_position] = 0;
 
-	return final_string;
+	return buffer;
 }
diff --git a/core/string/string_builder.h b/core/string/string_builder.h
index 1a989e8422cf..5b50ead81df4 100644
--- a/core/string/string_builder.h
+++ b/core/string/string_builder.h
@@ -32,21 +32,22 @@
 #define STRING_BUILDER_H
 
 #include "core/string/ustring.h"
-#include "core/templates/vector.h"
+#include "core/templates/local_vector.h"
 
 class StringBuilder {
 	uint32_t string_length = 0;
 
-	Vector<String> strings;
-	Vector<const char *> c_strings;
+	LocalVector<String> strings;
+	LocalVector<const char *> c_strings;
 
 	// -1 means it's a Godot String
 	// a natural number means C string.
-	Vector<int32_t> appended_strings;
+	LocalVector<int32_t> appended_strings;
 
 public:
 	StringBuilder &append(const String &p_string);
 	StringBuilder &append(const char *p_cstring);
+	void clear();
 
 	_FORCE_INLINE_ StringBuilder &operator+(const String &p_string) {
 		return append(p_string);
diff --git a/editor/gui/scene_tree_editor.cpp b/editor/gui/scene_tree_editor.cpp
index e89912d5bc68..4adab1c43c6e 100644
--- a/editor/gui/scene_tree_editor.cpp
+++ b/editor/gui/scene_tree_editor.cpp
@@ -32,6 +32,7 @@
 
 #include "core/config/project_settings.h"
 #include "core/object/script_language.h"
+#include "core/string/string_builder.h"
 #include "editor/editor_dock_manager.h"
 #include "editor/editor_file_system.h"
 #include "editor/editor_node.h"
@@ -511,24 +512,36 @@ void SceneTreeEditor::_queue_update_node_tooltip(Node *p_node, TreeItem *p_item)
 }
 
 void SceneTreeEditor::_update_node_tooltip(Node *p_node, TreeItem *p_item) {
+	// Use static StringBuilder to reuse inner buffer, avoiding memory allocation.
+	static StringBuilder tooltip;
+	tooltip.clear();
 	// Display the node name in all tooltips so that long node names can be previewed
 	// without having to rename them.
-	String tooltip = p_node->get_name();
+	tooltip += p_node->get_name();
 
 	if (p_node == get_scene_node() && p_node->get_scene_inherited_state().is_valid()) {
 		if (p_item->get_button_by_id(0, BUTTON_SUBSCENE) == -1) {
 			p_item->add_button(0, get_editor_theme_icon(SNAME("InstanceOptions")), BUTTON_SUBSCENE, false, TTR("Open in Editor"));
 		}
-		tooltip += String("\n" + TTR("Inherits:") + " " + p_node->get_scene_inherited_state()->get_path());
+		tooltip += "\n";
+		tooltip += TTR("Inherits:");
+		tooltip += " ";
+		tooltip += p_node->get_scene_inherited_state()->get_path();
 	} else if (p_node != get_scene_node() && !p_node->get_scene_file_path().is_empty() && can_open_instance) {
 		if (p_item->get_button_by_id(0, BUTTON_SUBSCENE) == -1) {
 			p_item->add_button(0, get_editor_theme_icon(SNAME("InstanceOptions")), BUTTON_SUBSCENE, false, TTR("Open in Editor"));
 		}
-		tooltip += String("\n" + TTR("Instance:") + " " + p_node->get_scene_file_path());
+		tooltip += "\n";
+		tooltip += TTR("Instance:");
+		tooltip += " ";
+		tooltip += p_node->get_scene_file_path();
 	}
 
 	StringName custom_type = EditorNode::get_singleton()->get_object_custom_type_name(p_node);
-	tooltip += "\n" + TTR("Type:") + " " + (custom_type != StringName() ? String(custom_type) : p_node->get_class());
+	tooltip += "\n";
+	tooltip += TTR("Type:");
+	tooltip += " ";
+	tooltip += custom_type != StringName() ? String(custom_type) : p_node->get_class();
 
 	if (!p_node->get_editor_description().is_empty()) {
 		const PackedInt32Array boundaries = TS->string_get_word_breaks(p_node->get_editor_description(), "", 80);
@@ -537,11 +550,12 @@ void SceneTreeEditor::_update_node_tooltip(Node *p_node, TreeItem *p_item) {
 		for (int i = 0; i < boundaries.size(); i += 2) {
 			const int start = boundaries[i];
 			const int end = boundaries[i + 1];
-			tooltip += "\n" + p_node->get_editor_description().substr(start, end - start + 1).rstrip("\n");
+			tooltip += "\n";
+			tooltip += p_node->get_editor_description().substr(start, end - start + 1).rstrip("\n");
 		}
 	}
 
-	p_item->set_tooltip_text(0, tooltip);
+	p_item->set_tooltip_text(0, tooltip.as_string());
 }
 
 void SceneTreeEditor::_node_visibility_changed(Node *p_node) {