Why? Because users will start abandoning your site if it takes them more than 2 seconds to see your site rendering in the browser, no matter how popular, informative and UI friendly your site is!
When we type and enter the URL (or click bookmark or search result) in the browser to get a web page, the following activities will happen and will take a few seconds to complete them:
1.the browser sends the HTTP request to the host server that the URL is pointing to
2.the host server receives the HTTP request, process it and then send the corresponding HTTP reply back to the browser
3.the browser receives the HTTP reply which likely will include a HTML file
4.the browser parses the HTML file, sends out HTTP requests to get the external objects (e.g. graphics) listed in the HTML file. The more number of external objects in the HTML file, the more requests the browser will send out
5.the browser receives HTTP replies and external objects, construct the page layout and display the web page
Activities (2) and (3) are called Back-End activities while (4) and (5) are called Front-End activities. Nowadays there are many objects such as graphics, video, style sheets and scripts etc. in a typical web page. We have a lot of HTTP requests and replies when we access a web page. If we plot the times for the browser to receive each HTTP replies against time, we will have a waterfall diagram similar to this one:
A lot of studies show that 80% of web site delivery time is Front-End related. In order to speed up the web content delivery, many techniques are developed to reduce the times used by Front-End activities. These techniques are called Front-End Optimization (FEO) or Web Performance Optimization (WPO).
The faster users can browse the Internet, the more frequent users will use (and search) the Internet. Yahoo! and Google spend huge effort to develop technologies and techniques to make the Internet faster! Yahoo! YSlow and Google PageSpeed are the most frequently used FEO references.
YSlow and PageSpeed share many common techniques and the following five are the most important ones:
1.reduce HTTP requests
2.leverage HTTP cache header
4.enable HTTP compression
5.use CDN, especially when your users spread across a large geographical area
Web site design and Search Engine Optimization (SEO) are two common focuses of companies who want to increase their website traffic, repeated visits and conversion rates. Many companies wonder why they have high bounce rates even if they have good site designs and SEO. Researches show that slow site is one of the major reasons. Users will find yours site beautiful and useful if and only if they can see it!
FEO improves web site performances. However FEO is a rather new concept and requires more technical knowledge to master. It needs more market education to help companies to adopt FEO to make their web sites faster.
If your site is slow, it doesn’t matter how cool is your site design and how high is your site ranking in search result.
On Internet, every second counts!