Turns out the simple implementation is faster on Python 3 so default …

…to that when falling back to pure python.

src/lazy_object_proxy/__init__.py

@@ -11,7 +11,7 @@
     from .cext import Proxy
     from .cext import identity
 except ImportError:
-    from .slots import Proxy
+    from .simple import Proxy
 else:
     copyreg.constructor(identity)