Hi Ryan,
I have one server with 4 CPU and 8GB RAM which is running out of memory regularly. It only runs a single XPage app and is 8.5.1. That server is slated for virtualization very soon and I will upgrade to 8.5.3 and if that does not resolve the issue I am going to do a major refactoring focusing on proper recycling in all document loops.
I have another server virtualized with 2 VCPUs and 3.25GB RAM that runs 20 XPage apps. It runs like a champ all the time without issue. It is 8.5.3.