Despite the fact that website speed looks like simple factor you can measure, it hides tricky questions: What website speed or page speed really means? It’s the speed by which the html is loaded? Or you have to measure the time in which the browser loads all the required files? Or time required by the browser to render the page? You should also include the time required to run the onload javascript code and widgets? If you think this post answers these questions you should stop reading it because it doesn’t. However, you’ll find out several ways to measure the page speed.
1. Simple Server Side Measurements.
Just calculate the page generation time on the fly. Inside your code you can record the time when the script begins and when it ends its execution for a http request. This incredible simple method can warn you if the code has some optimization leaks.
2.The main file loading speed.
You can measure in how much time the main file (.html, .php, …) is loaded. This simple metric can be measured by writing a simple http client which connects and load the file. Online tools are available here and here. You have to keep in mind that the loading time depends on the location of the client and on the location of the server.
3.Loading Time of all the files without running javascript.
A webpage is not properly loaded until the css file are not loaded. That’s why this measurement is closer to what happens when a human user opens the page. You can use this link to get the page loading speed.
4.Loading Time including Javascript Widgets
Most of the webpages contains external “widgets” wrote in javascript. Those widgets are loaded through javascript, either when they are encountered in the page, either after the page is loaded. The most known examples of such widgets are google adsense and google analytics. Every external widget will increase the page loading time so it would be good to know how much. For this purpose 2 firefox addons were created: YSlow(created by Yahoo) and Page Speed(create by Google). Both of them requred another firefox addon to run: Firebug.
Those 2 addons not only offer good metrics but they also offer good tips for improving in the tested page. Probably those are the best to use if you want to optimize a website.
5. Testing the page loading for high traffic.
A fast hosting is not always enough. You should check how your site respond when the page is requested by many users simultaneously. You can use LoadImpact online tool to check how the website will stand to a high traffic. If you read about digg effect you know that a high traffic volume can slow and even crash a server. Using the free version of this tool you can check how the website acts for 10 – 50 clients opening simultaneously a page. Using the paid version you can check up to 5000 clients. A fast hosting should be tested in this harsh conditions.