Given the languages they are using, I think it is fair to say that they are interested in system-programming kind of tasks, which for google means the stacks below what you normally use for web programming (i.e. I would expect google to have their own web servers, or at least heavily customized from existing ones, etc...). For system programming, "language speed" matters much more (one definition I like for system programming, seen on lambda ultimate: "programming where both algorithm complexity's constant and memory representation matter").
Of course, in most cases, you're right. Given an infinite pool of very good programmers and infinite time, C will almost always be faster than most other languages. But in reality, you have a very limited of maybe not so good programmers, and the project needed to be done yesterday :)
Of course, in most cases, you're right. Given an infinite pool of very good programmers and infinite time, C will almost always be faster than most other languages. But in reality, you have a very limited of maybe not so good programmers, and the project needed to be done yesterday :)