Well, that didn't take long…
Attempt 1:
Action: start > dug out cave > possessed keeper > moved in > un-possessed him > let sit
Result: Memory was at 50% when i let sit – was good for 3 minutes at 50% memory use. at 3 minutes or so, started moving up gradually until it hit 100% 1 minute later.
Attempt 2
Action: start > pause
Result: Exactly the same as above. memory was at 50% useage from the start… some 3-4 minutes later, it decided to climb, and then spiked 1 minute later.