Avoid the MRO loop in _make_cached_property_uncached if we can

Author: clayote

src/attr/_make.py

@@ -542,12 +542,15 @@ def _make_cached_property_uncached(original_cached_property_func, cls):
         "@property",
         defline,
         *doc_lines,
-        "    for entry in type.__dict__['__mro__'].__get__(self.__class__):",
-        f"        if '{name}_cache' in entry.__dict__:",
-        f"            descriptor = entry.__dict__['{name}_cache']",
-        "            break",
-        "    else:",
-        "        raise AttributeError('No descriptor')",
+        "    clsd = self.__class__.__dict__",
+        f"    descriptor = clsd.get('{name}_cache')",
+        "    if descriptor is None:",
+        "        for entry in type.__dict__['__mro__'].__get__(self.__class__)[1:]:",
+        f"            descriptor = entry.__dict__.get('{name}_cache')",
+        "            if descriptor is not None:",
+        "                break",
+        "        else:",
+        "            raise AttributeError('No descriptor')",
         "    try:",
         "        return descriptor.__get__(self, self.__class__)",
         "    except AttributeError:",