title: Does Codeigniter Autoloads Libraries/helpers on every Http Request
body: <p>I enabled profiling in my application based on Codeigniter and i got some surprising results.</p>
  
  <p>On further debugging i realized that the following values was very high even for a static pages like aboutus etc which has no DB interaction or php processing
  Loading Time: Base Classes 
  Controller Execution Time 
  Total Execution Time </p>
  
  <p>I tried playing with the config file and realized that if i removed the autoloading of several models and libraries the values of the above 3 variables goes significantly down</p>
  
  <p>I was assuming that if something is autoloaded once it remains in the memory. Is this right ?</p>
  
  <p>Also looking at the results if i have a model which is required 70% of the time in the code should i still not autoload it and load only when required to improve performance. </p>
  
  <p>Is there any other alternative</p>