title: C++, fastest way to get milliseconds since midnight
body: <p>This is code that will run often and have to run fast so I'd like to get some opinions on what the quickest implementation is.  Note, I actually need the full millisecond resolution to some degree of accuracy (so seconds * 1000 does not suffice). For this project, using Boost is OK.</p>
  
  <p>EDIT: The target platform is x64_86 CentOS5, also, hoping to be able to rely on the OS clock so I can also use this in a program that is not running continuously.</p>