I built a system that can hold 40,000 concurrent users with hardly 2 GiB of RAM, a bit of bandwidth (with a 300 Mbps connection it works great) using Capnproto

I built a system that can hold 40,000 concurrent users with hardly 2 GiB of RAM, a bit of bandwidth (with a 300 Mbps connection it works great) using Capnproto and that I am scaling horizontally. A server with 6 cores can hold at least 3 of these services. Now think of customers. How much you are going to save in operations? Loooooots! For backend efficiency and quality is still a critical metric, especially when operations are so cheap (tens of dollars per month).