When you have opened the waterfall report (see Where is the waterfall chart located?), you receive a large amount of data about your page and its elements. Each page element requires a request, TCP connect, HTTPS handshake, send, wait time, and receive time. The KB article Waterfall timings explains what is measured for these steps.
Once the receive time completes, the browser processes the element. A single page may have a hundred elements or more that the browser needs to process. The combined load times of the elements or just a sluggish few may cause your page to exceed your expected maximum load times. As you can see in the example below, this Full Page Check surpassed the 2.5-second maximum load time.
The report header gives general information about the check including the checkpoint used, the URL, and the browser used for the test. You will notice that the Result displays the specific reason for the error. This particular test failed due to exceeding the maximum load time with error code 6000. You can get explanations for other possible codes on the Error Types page.
So what exactly caused the error?
As you scroll down the page, you get a list of the page elements. The report lists the page elements in the order that they load in the browser. Some portions load synchronously, and some elements have dependencies and do not load until other elements on the page finish loading. To the right of each element, you see a bar graph. Each color band on the bar graph represents a different connection state. Placing the elements on a timeline shows them in a waterfall perspective. Color bands indicate the time each element took to load. By scanning the report, you can quickly see the page elements that took the longest for the browser to receive.
Viewing the request and response headers
At the bottom of the waterfall report, you can see the report summary. The first column contains the color legend for the color bars in the waterfall portion of the report. To the right, you can see the total time and the average time for each of the connection states. The rest of the report footer gives you element type counts and page totals.
Find the element source using domain groups
If your monitor is an FPC+, you can quickly see the source of your problem elements.
Remember the element number you want to examine from the waterfall report.
Click the Domains group button at the top right of the waterfall.
Locate the element number in the list to see the domain group.