Ian Lewis' Blog

I took a look at Twitter's code as an example of a site that gets lots of traffic and noticed a couple things.

1. They use Amazon S3 to store images
2. They split the javascript, favicons, and css up across 3 or 4 subdomains (assets0.twitter.com, assets2.twitter.com, etc.)
3. They include prototype and a version of jQuery as well as a version of script.aculo.us.

   	<script src="http://assets3.twitter.com/javascripts/prototype.js?1213829093" type="text/javascript"></script>
   	<script src="http://assets1.twitter.com/javascripts/effects.js?1213829093" type="text/javascript"></script>
   	<script src="http://assets0.twitter.com/javascripts/application.js?1213829093" type="text/javascript"></script>
   	<script src="http://assets0.twitter.com/javascripts/jquery-1.2.3.min.js?1213829093" type="text/javascript"></script>

It kind of surprised me that they include a version of prototype AND jQuery AND script.aculo.us since they aren't really light javascript files. Prototype comes in at 123kb, jQuery is 53kb, and script.aculo.us is 38kb. Seems to me that even with caching and all they could significantly reduce download traffic by sticking to one javascript library. I'm sure there is some wierd reason they do it though.