What Every Web Designer Needs To Know About Site Performance
WebSpeed Optimization Overview
Since Google’s recent announcement that web page load times are now a ranking factor web designers and developers have been required to pay additional attention to site performance considerations. Here are just a handful of considerations that today’s responsible web developers need to keep in mind.
Most of todays web pages are made up of a collection of components including CSS files, javascript, images and often movies. Minimising the number of elements and therefore the number of HTTP requests necessary to render a page is crucial for fast page load times.
Around 80% of the end user’s response time is consumed in waiting for all of the page elements to download. This waiting time is know to cause visitors to leave an ecommerce site and visit a faster loading competitor. Using a content delivery network to serve the static content, including javascript and CSS files, can significantly reduce this time. A content delivery network is basically a collection of servers setup in various geographic locations to efficiently deliver content to users.
As web designs become increasing complex, richer and more engaging to the end user they need an ever increasing number of components in order to render, such as Flash and javascript. On a first visit a number of HTTP requests are made in order to download these elements. If these are cached then there is less to download on a subsequent visit and this can be controlled using the ‘Expires’ header. This is commonly used for images but can be effectively used for all components including Flash and stylesheets.
Compression is another technique that every web developer should be using. GZIP is supported by around 90% of todays browsers and it can reduce the size of many elements by as much as 70%.
There are lots of additional techniques that are both good for search engine optimisation of web pages and will also improve the user experience. For example: stylesheets should be located at the top of pages and scripts at the bottom; both javascript and CSS files should be minified; and javascript and CSS should be in external files; also, reducing the number of DNS lookups and redirects is always a good idea. Good luck.
