Thanks for that article. As you said that we shouldn't use node for heavy calculations, but we are sending bulk sms, email, bill generation(for more than 2k-2.5k users in one set and there may be n number of sets running at a time). Now as I have already added Cluster, NGINX(at 3000), PM2, NSP do i need to worry about this task or I should change this calculations to other module/port/node or some other platform? One thing more, my project is running on a single port and module, how can I increase no. of ports and module (if I should) without changing much of the codes in my project?

P.S.: We are using aws n2.micro free tier, mongoDB in same ec2 instance. Userbase is already created so expecting more than 25k downloads by December. Is there anything more I should be concerned about? Thanks in advance.