To reproduce the issue clone the project, then yarn to install everything and then yarn start to start it up.
When you have it running, you can access the node.js's profiler tool in Chrome on localhost:7776. (you can find it at chrome://inspect)
Take a first heap snapshot after the app starts up and you'll see that it's pretty clean.
Then to simulate some load on the server download a tool like siege (that's what I'm testing with) and let it swarm the server for around 45 seconds (if you download siege then commad is siege http://localhost:3005). You can watch live how the server's heap size is growing to end up at least twice as big, mostly clogged by FrameLoop.