Memory compaction

Both swapping out a page and freeing something that was recently used has performance impacts, so if you can get away with doing less of that while simultaneously reducing memory fragmentation, that seems like a good thing.

What, as I understand it, Jon says is that if the code finds a page it would like to move, which it cannot do, but it can reclaim that page, it will do that instead of moving it, thereby also freeing it for the contiguous memory block it is creating.