title: vector::operator[] overhead
body: <p>Apparently, after profiling my (scientific computation) C++ code, 25% (!) of the time is spent with calls to <code>vector::operator[]</code>.  True, my code spends all of its time reading and writing in <code>vector&lt;float&gt;</code>s (and a few <code>vector&lt;int&gt;</code>s too), but still, I'd like to know if there's supposed to be some significant overhead of <code>operator[]</code> compared to C-style arrays?</p>
  
  <p>(I've seen another related question on SO, but regarding <code>[]</code> vs <code>at()</code> -- but apparently even <code>[]</code> is too slow for me?!)</p>
  
  <p>Thanks,
  Antony</p>
  
  <p>(edit: just for info: using g++ -O3 version 4.5.2 on Ubuntu)</p>