diff --git a/Lib/enum.py b/Lib/enum.py
index f97a5193492e602..7aff36c94ce1dcf 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -1620,10 +1620,14 @@ def __or__(self, other):
         if other_value is NotImplemented:
             return NotImplemented
 
-        for flag in self, other:
-            if self._get_value(flag) is None:
-                raise TypeError(f"'{flag}' cannot be combined with other flags with |")
         value = self._value_
+        # _get_value(self) is self._value_ and _get_value(other) is
+        # other_value, so only walk the operands (to raise on the offending
+        # flag) when one of those values is actually None.
+        if value is None or other_value is None:
+            for flag in self, other:
+                if self._get_value(flag) is None:
+                    raise TypeError(f"'{flag}' cannot be combined with other flags with |")
         return self.__class__(value | other_value)
 
     def __and__(self, other):
@@ -1631,10 +1635,11 @@ def __and__(self, other):
         if other_value is NotImplemented:
             return NotImplemented
 
-        for flag in self, other:
-            if self._get_value(flag) is None:
-                raise TypeError(f"'{flag}' cannot be combined with other flags with &")
         value = self._value_
+        if value is None or other_value is None:
+            for flag in self, other:
+                if self._get_value(flag) is None:
+                    raise TypeError(f"'{flag}' cannot be combined with other flags with &")
         return self.__class__(value & other_value)
 
     def __xor__(self, other):
@@ -1642,10 +1647,11 @@ def __xor__(self, other):
         if other_value is NotImplemented:
             return NotImplemented
 
-        for flag in self, other:
-            if self._get_value(flag) is None:
-                raise TypeError(f"'{flag}' cannot be combined with other flags with ^")
         value = self._value_
+        if value is None or other_value is None:
+            for flag in self, other:
+                if self._get_value(flag) is None:
+                    raise TypeError(f"'{flag}' cannot be combined with other flags with ^")
         return self.__class__(value ^ other_value)
 
     def __invert__(self):
diff --git a/Misc/NEWS.d/next/Library/2026-06-02-15-44-57.gh-issue-150817.lpFCh0.rst b/Misc/NEWS.d/next/Library/2026-06-02-15-44-57.gh-issue-150817.lpFCh0.rst
new file mode 100644
index 000000000000000..42532bb0222cf4e
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-06-02-15-44-57.gh-issue-150817.lpFCh0.rst
@@ -0,0 +1,2 @@
+Speed up the ``|``, ``&`` and ``^`` operations on :class:`enum.Flag` members.
+Patch by Bernát Gábor.