Periodic OOMKiller events - how to track memory usage?

My HA server is running standalone on an 8GB x86 ZimaBoard. On the console, I periodically see messages from the OOMKiller, along with periodic connection drops from the webpage/iOS app.

When I look at the Settings/System/Hardware page, it’s showing ~89% memory usage, which seems high, and is probably the cause of the OOMKiller events.

What’s less clear is where the memory is going, and what I can do to reduce it.

Looking at the various addon pages, nothing really stands out.

Where should I go to figure out where the memory is going?