Are you using that for something?
Everything else looks normal.
That actually seems rather large. Mine is only 2.4M and I have some pretty large objects. Also, I think that only measures things you've set to use the filesystem store, so what is in memory will potentially be much larger.
It would be good if you could measure the resource uses of Node-RED when it crashes if you can. On my 6GB RAM i5, Node-RED is using 11.0G of virtual memory, 206M resident, 40993b of shared (2.7% of memory) according to htop.
Clearly something in Node-RED is sucking up all of the available heap if it won't even start. That implies that you have something using that heap almost as soon as it starts. That might not be something actually using all the memory, it could be that node.js is trying to copy/move something in memory that is too large and so it can't find a big enough slot to handle it.
One other thing you can do is turn the Node-RED log level to max so that you can see more clearly when it crashes and what it was doing just before.
