Have you given dask a try? It gives you out-of-core arrays with numpy semantics and distributed computing.
If you can't make the core pandas code decently fast, dask won't save you.
I've had success using it on non vanilla stuff (i.e. code that could not get converted to play natively with numpy/pandas structures)
As a bonus, the nice profiling tools (built within dask) have also helped me improve the performance of the code.