I just started up a GenServer to hold a list of Strings, and added ~1mil characters at a time until I got to several hundred MB memory usage. No noticeable slowdown, neither with inserting new data, nor retrieving the data. Obviously this is not a very robust test, but it’s enough for me to think that if there is a performance issue, it would probably be from an inefficient update algorithm, or insufficient hardware, rather than a limitation of GenServer itself.

Ah yes - let me give more context

• Games are pretty ephemeral; they are tracked entirely in memory during gameplay - they only last like 5 minutes and are not high stakes. I’m not worried about recovering a game in progress if it crashes.
• A game consists of multiple rounds (between 3-10 rounds)
• A game room has between 2-10 players in it, but I’m hoping to have many more at some point..
• Every round, every player in the game submits a json blob payload to the server with a max size of ~4kb. This is where significant mem usage would accumulate over time in storing the history. I ultimately store these blobs in a json column in Postgres.

While I do know that Agents and ETS are also just in-memory storage solutions, I’m wondering if it’d be advantageous to split up the state between multiple processes vs just the one genserver.