title: Why is istream/ostream slow
body: <p>At 50:40 of <a href="http://channel9.msdn.com/Events/GoingNative/2013/Writing-Quick-Code-in-Cpp-Quickly" rel="noreferrer">http://channel9.msdn.com/Events/GoingNative/2013/Writing-Quick-Code-in-Cpp-Quickly</a> Andrei Alexandrescu makes a joke about how not efficient/slow istream is.</p>
  
  <p>I had an issue in the past with ostream being slow and fwrite being significantly faster (reducing many seconds when running the main loop once) but I never understood why nor looked into it.</p>
  
  <p>What makes istream and ostream slow in C++? or at least slow compared to other things (like fread/fget, fwrite) which would equally satisfied the needs.</p>