I think it is obsolete in that area, and has been for years (decades? Unoptimized SQL is almost always slower than key-value stores). General purpose programming is really about meeting user & business requirements. Speed and ffficiency is a second level concern, which only becomes an issue when you don't have enough of it.
BUT efficiency is even more important now for systems-level program ("system" in the sense of building libraries for use by other systems, as opposed to user-facing).
A good example is SnappyLabs who developed a faster JPEG encoder and ended up being a subject of a Google/Apple bidding war.