diff --git a/fixtracks/utils/merger.py b/fixtracks/utils/merger.py
index 2dfc02c..a67bd58 100644
--- a/fixtracks/utils/merger.py
+++ b/fixtracks/utils/merger.py
@@ -56,28 +56,23 @@ class Merger(QRunnable):
         numpy.ndarray
             2D array, Coordinates of the bounding box for each detection. Shape: (num_detections, 4) x1, y1, x2, y2
         """
+        x = lambda kp: np.array([float(kpp) for kpp in kp[1:-1].split(",")])
         logging.info("Converting to numpy ...")
+        # from IPython import embed
+        # embed()
+        dimensions = 2
         key_columns = [c for c in df.columns if "key_" in c]
         box_columns = [c for c in df.columns if "box_" in c]
-        num_frames = len(df)
-        num_keypoints = len(key_columns)
-        dimensions = 2
-        keypoints = np.empty((num_frames, num_keypoints, dimensions))
-        visibility = np.empty((num_frames, num_keypoints))
-        boxcoordinates = np.empty((num_frames, 4))
-
-        for i, row in df.iterrows():
-            for j, k in enumerate(key_columns):
-                key_data = row[k]
-                l = list(map(float, list(key_data[1:-1].split(","))))
-                keypoints[i, j, :] = l
-            for j, b in enumerate(box_columns):
-                boxcoordinates[i, j] = row[b]
-            if isinstance(row["visible"], str):
-                vis = list(map(float, row["visible"][1:-1].split()))
-                visibility[i, :] = vis
-            else:
-                visibility[i, :] = row["visible"]
+        keypoints = np.empty((len(df), len(key_columns), dimensions))
+        visibility = np.empty((len(df), len(key_columns)))
+        boxcoordinates = np.stack([df[b].values for b in box_columns]).astype(np.float32).T
+        temp_v = df.visible.values
+        temp_k = np.stack([df[k].values for k in key_columns]).T
+        for i, k in enumerate(temp_k):
+            temp = np.array([x(kp) for kp in k])
+            keypoints[i, :, :] = temp
+            visibility[i,:] = [float(val) for val in temp_v[i][1:-1].split()]
+
         logging.info("Converting to numpy done!")
         return keypoints, visibility, boxcoordinates