The serialization/deserialization times are dramatically different for Python. Thrift has an accelerated binary serializer written in C with Python bindings, while Protobuf's is pure Python. While there exist third party C++ wrappers for Protobuf in Python as well, they are buggy (segfaults).
This is ultimately the reason we chose Thrift over PB when developing our app (zite). Thrift was over 40 times faster in serialization for our python code.
