Hi Lewis, I can't quite simulate it exactly over here because I've only got 16GB, and when that gets filled up yes performance goes way downhill but that's just what I'd expect.

I think it's possible that the sluggish performance you were seeing is still related to a type of paging similar to swapping to disk. There are some other circumstances where that can happen other than just running out, like if you minimize a program's main window its working set is trimmed and then page faults will occur for any touched pages to bring them back to the active working set. (see https://support.microsoft.com/en-us/help/293215/the-working-set-of-an-application-is-trimmed-when-its-top-level-window). When there is a really large amount of memory involved all these operations done by the OS take more time to finish.

- Michael