# UNDF: UNDF-2026-000000722
--- a/distlib/util.py
+++ b/distlib/util.py
@@ -1,6 +1,6 @@
 import codecs
-from collections import deque
+from collections import deque, OrderedDict
 import contextlib
@@ -1127,16 +1127,16 @@ def get_steps(self, final):
         if not self.is_step(final):
             raise ValueError('Unknown: %r' % final)
-        result = []
-        todo = []
+        result = OrderedDict()  # preserves insertion order, O(1) move_to_end
+        todo = deque()          # O(1) popleft instead of O(N) list.pop(0)
         seen = set()
-        todo.append(final)
+        todo.append(final)      # deque.append is O(1)
         while todo:
-            step = todo.pop(0)
+            step = todo.popleft()   # O(1) instead of O(N) list.pop(0)
             if step in seen:
                 # if a step was already seen,
                 # move it to the end (so it will appear earlier
                 # when reversed on return) ... but not for the
                 # final step, as that would be confusing for
                 # users
                 if step != final:
-                    result.remove(step)  # O(N) list scan
-                    result.append(step)
+                    result.move_to_end(step)  # O(1) OrderedDict relink
             else:
                 seen.add(step)
-                result.append(step)
+                result[step] = None
                 preds = self._preds.get(step, ())
                 todo.extend(preds)
-        return reversed(result)
+        return reversed(list(result))