title: Javascript and CSS parsing performance
body: <p>I am trying to improve the performance of a web application.  I have metrics that I can use to optimize the time taken to return the main HTML page, but I'm concerned about the external CSS and JavaScript files that are included from these HTML pages.  These are served statically, with HTTP Expires headers, but are shared between all the pages of the application.</p>
  
  <p>I'm concerned that the browser has to parse these CSS and JavaScript files for each page that is displayed and so having all the CSS and JavaScript for the site shared into common files will negatively affect performance.  Should I be trying to split out these files so I link from each page to only the CSS and JavaScript needed for that page, or would I get little return for my efforts?</p>
  
  <p>Are there any tools that could help me generate metrics for this?
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