From 9234769e6612b30dba6318b01431c4c6064f16af Mon Sep 17 00:00:00 2001
From: Randolf Scholz <randolf.scholz@gmail.com>
Date: Thu, 16 Nov 2023 14:25:05 +0100
Subject: [PATCH] added fast check in _ProtocolMeta.__instancecheck__

---
 Lib/typing.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Lib/typing.py b/Lib/typing.py
index 14845b36028ca1..911dcd096e7e7b 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -1850,6 +1850,11 @@ def __instancecheck__(cls, instance):
         if super().__instancecheck__(instance):
             return True
 
+        # quick true negative check for protocols with many attributes.
+        if not hasattr(instance, '__getattr__'):
+            if not (cls.__protocol_attrs__ <= set(dir(instance))):
+                return False
+
         getattr_static = _lazy_load_getattr_static()
         for attr in cls.__protocol_attrs__:
             try: