One of Sutter's argument is that C++ is more cost-efficient in a data center due to lower energy costs. Yet, I haven't heard of many SaaS applications developed

One of Sutter's argument is that C++ is more cost-efficient in a data center due to lower energy costs. Yet, I haven't heard of many SaaS applications developed in C++. The Rails-style "just throw more servers at it" way is still very popular (which Sutter mentions as optimizing for programmer productivity). I suppose for startups the answer is to eschew premature optimization (for cost) and get the MVP done as quickly as possible (optimizing for programmer productivity). And, if and when demand requires, invest enough to optimize the bottlenecks.