It's not something that can be easily benched because it depends a lot of the use case. If some conditions are present (big amount of data sent to XML-RPC, the XML-RPC server taking a long time to answer, end either Python giving back the memory to the OS or another thread reusing the garbage collected memory) the gain in memory can be very significant, in most other cases, it won't change anything. 

Do you me to craft a simple example where the difference can be seen ?