1.13 cross-platform server.jar memory climbing

I started the 1.13 server.jar and without anyone joining it or running any commands, the memory started to climb. It steadily climbed until it reached 3% memory free and then it drops and resets to around 36% memory free. I've tested the 1.12 server.jar and the memory use remains completely steady while nothing major happens. I'm assuming it's a 1.13 only problem.