Chapter 2. What’s Slowing Down My Page?

It’s good to know how fast a page is. Knowing how to make it faster is even better. Knowing the change in performance over time is extremely important to validating that the optimizations to the page are actually working. Before any optimizations can be made, however, you need to understand how the page is put together and what opportunities exist for optimization. To get there, this chapter will walk you through the steps of running a very simple test and analyzing the results to figure out what exactly is going on under the hood.

Running a Simple Test

Almost everyone who starts out with WebPageTest goes through the home page, which acts as the gateway to the rest of the tool. Putting ourselves in the shoes of someone who has never used the tool before, let’s try to run our first test.

First, go to One of the most prominent parts of the page is the great big text-input field, with a prompt to Enter a Website URL (Figure 2-1). Let’s get started by providing the web address of a page we want to test (Figure 2-2).

uwpt 0201
Figure 2-1. The default WebPageTest home page
uwpt 0202
Figure 2-2. The URL field of the home page set to

At this point, you may either be feeling overwhelmed by all of the other configuration options ...

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