As you know, your website speed impacts user experience, is used as a ranking factor by search engines and can increase your web traffic.
After taking steps to improve your website performance, such as using a WordPress caching plugin, you might be looking to test your website speed and see how it compares to other sites.
One interesting tool you can use is whichloadsfaster. It lets you have a website speed race against another site. Here is the result for my site vs. CNN .
GTmetrix provides great information on your Google site/page speed and indicates the most important improvement areas for your website. In addition to the Google Page Speed overview, do have a look at the Timeline as well. This displays the load time for different components of your site. I don’t bother with the YSlow score because it is often wrong and doesn’t capture things like use of a Content Deliver Network, even though I’m using a CDN.
It is also possible to install a Page Speed extension for Chrome/Firefox, so that you can test website speed quickly in your browser.