Method caching of dynamic objects

I instantiate a dynamic object by using the Activator.CreateInstance() method, e.g:
dynamic dynObject = Activator.CreateInstance(Type.GetTypeFromProgID("SomeProgID"));

The object created is a COM object with lots of methods (hundreds) defined and it takes quite some time to run a method the first time due to the runtime going through the objects capabilities (methods etc.) and caching them, in this case approx. 1500ms.

Say I need less than 10% of the objects offered interface, is it possible to restrict the runtime to cache only a specified set of methods, e.g. by a method pattern or similar ? (possibly increase the cache later if needed).

I have tried using reflection instead and it is initially faster, later slower and of course much more complex and error prone.