title: Does using large libraries inherently make slower code?
body: <p>I have a psychological tic which makes me reluctant to use large libraries (like <a href="http://library.gnome.org/devel/glib/stable/" rel="noreferrer">GLib</a> or <a href="http://www.boost.org/" rel="noreferrer">Boost</a>) in lower-level languages like C and C++. In my mind, I think:</p>
  
  <blockquote>
    <p>Well, this library has thousands of
    man hours put into it, and it's been
    created by people who know a lot more
    about the language than I ever will.
    Their authors and fans say that
    the libraries are fast and reliable,
    and the functionality looks really
    useful, and it will certainly stop me
    from (badly) reinventing wheels.</p>
    
    <p>But damn it, I'm never going to use
    every function in that library. It's
    too big and it's probably become bloated
    over the years; it's another ball 
    and chain my program needs to drag around.</p>
  </blockquote>
  
  <p>The <a href="http://thread.gmane.org/gmane.comp.version-control.git/57643/focus=57918" rel="noreferrer">Torvalds rant</a> (controversial though it is) doesn't exactly put my heart at ease either.</p>
  
  <p>Is there any basis to my thinking, or am I merely unreasonable and/or ignorant? Even if I only use one or two features of a large library, by linking to that library am I going to incur runtime performance overheads?</p>
  
  <p>I'm sure it depends too on what the specific library is, but I'm generally interested in knowing whether large libraries will, at a technical level, inherently introduce inefficiencies.</p>
  
  <p>I'm tired of obsessing and muttering and worrying about this, when I don't have the technical knowledge to know if I'm right or not.</p>
  
  <p>Please put me out of my misery!</p>