Is this an optimization?

Question

Does going from

<script type="text/javascript" src="jquery.js"></script>

to

<script type="text/javascript">
  <?php echo file_get_contents('jquery.js'); ?>
</script>

really speed things up?

I am thinking it does because php can fetch and embed a file's contents faster than the client's browser can make a full request for the file, because php isn't going over the network.

Is the main difference that the traditional method can be cached?

Answer 1

It may be faster on the first page load, but on every subsequent load it will be much slower. In the first example, the client browser would cache the result. In the second, it can not.

Answer 2

If you only ever serve one single website in your client's life, then yes, because you only have one HTTP request instead of two.

If you are going to serve multiple sites which all link to the same javascript source file, then you're duplicating all this redundant data and not giving the client a chance to cache the file.