In the node.js version of NarraFirma, if you are working with a lot of stories, you could see an error having to do with the Javascript heap (memory allocation). This is easily fixed. Just add an extra parameter when you start your server, thus:
$ node –max-old-space-size=4096 NarraFirmaServer.js
This will increase the amount of memory available above the default of 512 megabytes.