Relinquishing resouces question

In Options > Audio I have the computer set to relinquish resources when I remove a plug-in and yet some large plug-ins that normally take a long time to load, load instantly if I remove and reload them. If the samples are removed from RAM when I unload, it should take a long time when I reload. The instant reload suggests that the system finds the samples already there. Does anyone know the technical side of that behavior? It seems to me that the samples are still there (hence the quick reload) but as long as the plug is not loaded, the system has the memory is marked as 'available'? Thanks - rev