Is it possible to manually define the logic of the serialization used for AppEngine Datastore?
I am assuming Google is using reflection to do this in a generic way. This works but proves to be quite slow. I'd be willing to write (and maintain) quite some code to speed up the serialization / deserialization of datastore objects (I have large objects and this consumes quite some percentage of the time).
The datastore uses Protocol-Buffers internally, and there is no way round, as its the only way your application can communicate with the datastore. (The implementation can be found in the SDK/google/appengine/datastore/entity_pb.py) If you think, (de)serialization is too slow in your case, you probably have two choices