diff --git a/codeflash/code_utils/instrument_existing_tests.py b/codeflash/code_utils/instrument_existing_tests.py
index db08f8afc..a0c44804f 100644
--- a/codeflash/code_utils/instrument_existing_tests.py
+++ b/codeflash/code_utils/instrument_existing_tests.py
@@ -312,6 +312,8 @@ def __init__(
         self.async_call_counter: dict[str, int] = {}
         if len(function.parents) == 1 and function.parents[0].type == "ClassDef":
             self.class_name = function.top_level_parent_name
+        # Cache for _is_target_call type decisions
+        self._function_name = function.function_name
 
     def visit_ClassDef(self, node: ast.ClassDef) -> ast.ClassDef:
         # Add timeout decorator for unittest test classes if needed
@@ -397,30 +399,37 @@ def _process_test_function(
         return node
 
     def _instrument_statement(self, stmt: ast.stmt, _node_name: str) -> tuple[ast.stmt, bool]:
-        for node in ast.walk(stmt):
+        # Optimize ast.walk: Stop traversal immediately after matching Await/Call/target
+        stack = [stmt]
+        while stack:
+            node = stack.pop()
+            # The following 'isinstance' is fast, so keep order
             if (
                 isinstance(node, ast.Await)
                 and isinstance(node.value, ast.Call)
                 and self._is_target_call(node.value)
                 and self._call_in_positions(node.value)
             ):
-                # Check if this call is in one of our target positions
                 return stmt, True  # Return original statement but signal we added env var
-
+            # Only traverse children if this isn't Await with target (otherwise redundant)
+            for child in ast.iter_child_nodes(node):
+                stack.append(child)
         return stmt, False
 
     def _is_target_call(self, call_node: ast.Call) -> bool:
         """Check if this call node is calling our target async function."""
-        if isinstance(call_node.func, ast.Name):
-            return call_node.func.id == self.function_object.function_name
-        if isinstance(call_node.func, ast.Attribute):
-            return call_node.func.attr == self.function_object.function_name
+        func = call_node.func
+        if isinstance(func, ast.Name):
+            # Early-exit style, as attribute hits are rare
+            return func.id == self._function_name
+        if isinstance(func, ast.Attribute):
+            return func.attr == self._function_name
         return False
 
     def _call_in_positions(self, call_node: ast.Call) -> bool:
+        # Inline hasattr test and use direct call to node_in_call_position (already optimal)
         if not hasattr(call_node, "lineno") or not hasattr(call_node, "col_offset"):
             return False
-
         return node_in_call_position(call_node, self.call_positions)