Lately most of the web developers are talking more and more about optimization. One of the practices everybody’s supporting is to use cookie free domains for static content. First of all, what’s static content. That, in breve, are all images, JavaScripts and CSS. That’s everything that’s transmitted to the client with no change from the server at all. In a typical PHP/MySQL site everything generated on the server site is considered dynamic, while every component that’s given to the client with no change is static. That’s why they don’t need cookies in the request.

That’s what Yahoo! YSlow says:

In a short example, lets say you’ve a web page with 10 background images used by its CSS file. Here’s a good practice to combine them in one or even use base64 for them, but that’s another talk. So in that scenario you’ll send all the cookies you’ve on the site with this images, but actually they don’t profit at all from this. The question is why you should send all this data with no need? Won’t you benefit from sending it with no cookies.

As it sound logical I read some articles recently describing that the benefit from putting the static content on a non-cookie domain doesn’t pays back. OK it may be strange, however every 40 ms or whatever of page load is important, aren’t they?

Setup a Cookie Free Domain

The problem is that if you’d like to setup a cookie free domain the things are becoming a bit harder. You’ve two options:

1. Move all your static content on a different domain, where no cookies are set.
2. Move your static content on a different sub domain and set all the cookies to the www subdomain. (Here’s a bit tricky).

All this indeed a bit tricky! So let me proceed with the next topic.

Benefits from CDN

A CDN or Content Delivery Network is a term become famous with the growing web. Now big sites have servers in almost every continent and perhaps country. CDN is an abstraction of all this. The good thing is that there’s supposed to be stored static content. Think about the YouTube’s video files. Another good thing is that this domains are cookie free by default. The thing is …

Why don’t You Combine Them?

You’ll benefit from both ideas. Cookie free domains with CDN. In one side the web page will benefit from the closest location of the server and the CDN and in other side all this will come with no cookies to you. That’s really nice and most of the time people thing of CDN for only storing large scale data, such as video files, but no one says you cannot put your CSS, JavaScripts and background images there!

• HTML
• CSS
• JavaScript
• Flash or Silverlight
• Server side scripting language, like PHP, ASP or whatever
• Database server

I’d like to add one category more and that’s the images we use in every website to construct the desirable layout. They are extremely important when optimizing a web page, because almost always they make more than half of the traffic of a page.

In few posts I’ll write what and how can be optimized, according to my experience and according to the articles I’ve read. I won’t mention again why the optimization is important – I’ve written already some posts about that and the web is full of articles.

As I can say nowadays this is the most important topic of the web development. Almost everyone’s speaking about it and I’d like to give some references in my talks, just to make it more clear and to give you some basic points from where you can start optimizing.