title: Are there significant performance gains inherent in using .NET's built in classes?
body: <p>Quick little question...</p>
  
  <p>I know that sometimes in other languages libraries have part of their code written in platform-specific straight C for performance reasons. In such cases you can get <em>huge</em> performance gains by using library code wherever possible.</p>
  
  <p>So does the .NET platform do this? Is Microsoft's implementation of the Base Class Library optimized in some way that I can't hope to match in managed code?</p>
  
  <p>What about something little like using KeyValuePair as a type-safe tuple struct instead of writing my own?</p>