C++ solution (the solution you didn't ask for, sorry) for saving to disk from memory (as some sort of periodic expensive sync) would be to write a stream operator for your objects and stream them to disk. Loading would involve reading them back; would only work on the same OS and architecture.

Alternative approach: For Windows, you could just use disk but pass FILE_ATTRIBUTE_TEMPORARY to CreateFile to force it to be in memory if the file is small enough.