It is well documented that asset files that don’t need cookies are wasting precious time in the round trip from user request (browser request) through to the full rendering a web page.
If you are reading this then I’m assuming that you have a good understanding of a website served from and LAMP setup and therefore a good understanding of Linux, Apache, MySQL and PHP. This is not a recipe, but a set of notes on how we achieved certain optimisations for our websites.
Obviously this can vary from site to site, but the principal holds.
Google Talk about this is here.
There are two things you can do about this:
You can concatenate files yourself or use a tool to do it for you such as W3 Total Cache (see minify).
If you are using a cache for wordpress and I tend to like W3 Total cache, then by caching dynamic pages and serving them as static HTML, you have to be careful with certain things. If you have any content on each page that is specific to that user then that needs to be fetched by AJAX. On my e-commerce sites the shopping basket details displayed on each page are handled this way and I consider it well worth the extra time coding to all page caching. All other aspect of each page are the same between users and only change when we alter product particulars, such as price, description or images – perfect for caching. See shopp’s instructions on caching.
Shopp offers an AJAX cart (and side cart), but it doesn’t offer an AJAX update of the number of items and their value in the the cart, so that it has to be coded.
If my site is on www.mysite.com, then I have setup static.mysite.com and pointed it to part of the same webroot by creating a symbolic link to the wp-contents directory.
In addition you will need to convert the URLs returned from shopp(‘product’ in the shopp templates files to use the static domain: be careful not to ignore the https case, you don’t want mixed content on your secure pages.