diff --git a/native_bridge/debug/test_g15_stress.py b/native_bridge/debug/test_g15_stress.py
index 14afc70..c390e1c 100644
--- a/native_bridge/debug/test_g15_stress.py
+++ b/native_bridge/debug/test_g15_stress.py
@@ -55,19 +55,20 @@ def log_lines():
 def wait_log(pattern, timeout, since):
     end = time.time() + timeout
     while time.time() < end:
-        for i in range(since, len(log_lines())):
-            if pattern in log_lines()[i]:
-                return log_lines()[i]
+        lines = log_lines()
+        for i in range(since, len(lines)):
+            if pattern in lines[i]:
+                return lines[i]
         time.sleep(0.2)
     return None
 
 def wait_gui(ch, timeout, since):
     end = time.time() + timeout
     while time.time() < end:
-        for i in range(since, len(log_lines())):
-            l = log_lines()[i]
-            if "GUI attached hwnd=" in l and f"ch={ch}" in l:
-                return l
+        lines = log_lines()
+        for i in range(since, len(lines)):
+            if "GUI attached hwnd=" in lines[i] and f"ch={ch}" in lines[i]:
+                return lines[i]
         time.sleep(0.2)
     return None