This is one reason why I'm very excited about Python's new AsyncIO module in Python 3 only. It's asyncore done right, and is a great way to write network applications. I look forward to seeing what is built on top.
I hear this all the time but it really doesn't square up with my personal experiences. I've had to re-implement dynamic language stuff in C++ many times to get acceptable performance. No real design changes, just straight ports to C++. The entire value proposition of Golang is that the scripting language dynamic type systems are too slow, and it seems like loads of folks agree.
Performance in a certain sense isn't just speed of a single uncoupled module, but also the end-to-end seamlessness of a system. The higher level languages might 'waste' 300ms in every function call, but save perhaps years in development time.
Also- architecting and developing medium-sized projects is not just the 'ENTERPRISE THING' anymore. A vastly greater number of people now have a-shot-at larger projects. So this creative freedom and technical UN-chaining also add to performance in a very in-direct way by allowing better minds to enter the game.