diff --git a/Week04/decorators_gokay_sahin.py b/Week04/decorators_gokay_sahin.py
new file mode 100644
index 00000000..ccbe8f43
--- /dev/null
+++ b/Week04/decorators_gokay_sahin.py
@@ -0,0 +1,40 @@
+import time
+import tracemalloc
+
+def performance(fn):
+    """
+    Decorator to measure performance of a function, including
+    execution time and memory usage.
+
+    This decorator tracks:
+    - The number of times the function is called.
+    - The cumulative time taken by the function.
+    - The cumulative peak memory usage.
+
+    :param fn: The function to be wrapped and measured.
+    :return: The result of the wrapped function.
+    """  
+    if not hasattr(performance, 'counter'):
+        performance.counter = 0
+        performance.total_time = 0
+        performance.total_mem = 0
+
+    def wrapper(*args, **kwargs):
+        tracemalloc.start()
+
+        time_before = time.time()
+
+        result = fn(*args, **kwargs)
+
+        time_after = time.time()
+
+        curr_mem, peak_mem = tracemalloc.get_traced_memory()
+        tracemalloc.stop()
+
+        performance.counter += 1
+        performance.total_time += (time_after - time_before)  
+        performance.total_mem += peak_mem  
+
+        return result
+
+    return wrapper