I think the answer for efficiency in programming is to reduce the total number of servers, data centers and bandwidth required to deliver the solution. Picking

I think the answer for efficiency in programming is to reduce the total number of servers, data centers and bandwidth required to deliver the solution. Picking a programming language has virtually no bearing on this. There are certainly some languages that can run faster in some scenarios, but these microbenchmarks have little relevance to any practical reality at scale. For me, I like to go though hell instead of around it. Don't try to make one server sip the power obsessively. Make that one server do as much as possible, since you are already paying a fixed, idle power cost. I think picking things like SQLite vs SQL Server have a much bigger impact on power consumption. These are less disruptive choices than swapping programming languages as well.