Grande pergunta! Eu me perguntava sobre isso também.
Acontece que existem melhorias maciças para o RDP com o Windows 8. Você pode ler sobre melhorias gráficas para RDP no blog de Área de Trabalho Remota da Microsoft.
Para responder especificamente à sua pergunta, aqui está uma citação deste blogue:
In Windows Server 2012 and Windows 8, the full local desktop is composed and rendered on the host in a remote session before the resulting image is encoded and sent by RemoteFX. In other words, RemoteFX is based on host-side rendering. As a result, the full desktop experience of the Windows 8 desktop as well as all application user interfaces (UIs) is consistently sent remotely at the highest quality with 32 bits per pixel (BPP). To balance user experience with encoding and bandwidth cost, the target frame rate in a remote session is 30 frames per second (FPS).