Optimized Model instantiation a bit.

* Avoid some unnecessary attribute lookups, e.g. access signals directly rather than from module
* Alias some repeat accesses inside the method to use the slightly faster local lookups
* Use tuple to iterate remaining kwargs as it's faster to construct
* Cache Field.get_default() to avoid running through all the logic on every call
* Use a cached list of the properties on the model class to avoid repeat isinstance() calls

django/db/models/options.py

@@ -883,3 +883,14 @@ class Options(object):
     @has_auto_field.setter
     def has_auto_field(self, value):
         pass
+
+    @cached_property
+    def _property_names(self):
+        """
+        Return a set of the names of the properties defined on the model.
+        Internal helper for model initialization.
+        """
+        return frozenset({
+            attr for attr in
+            dir(self.model) if isinstance(getattr(self.model, attr), property)
+        })