A Quick Guide to GTmetrix

If you aren’t familiar with web development, grasping which features of your site are making your site load slowly can be puzzling. Page loading speed is a vital SEO metric which can be difficult to exploit in your favor.

GTmetrix is a tool which assists you to analyze the loading speed of you website for free.

You can re-test the page after you make changes, compare the page to other pages, and setup alerts and monitoring – if you’re a registered user.

You’ll also be able to download your analysis to a PDF or share it with someone else.

An overall performance score for the site is given—how fast it loads, how large the page is, and how many people have tried to visit it recently.

Important Considerations Before Analyzing Your Website

An accurate measurement of load time of a site can be difficult to achieve, because many factors could play into the results you receive. A single speed test will not be sufficient, as some of the factors will be affected by:

  • Current server load (and even more if you share a server)
  • Number of current visitors
  • The user’s connection speed
  • The user’s proximity to your server

You should do multiple speed tests at different times of the day, week, and perhaps even month, collecting data from one test per hour for a week or two. An average from these tests will be a much more accurate page load speed.

What does GTmetrix do?


You can compare your site (and others) in the compare tool. It shows you the grades of each site and highlights the winner in green.

Don’t worry if you don’t ‘win’ against your competition on every metric, but there may be some areas where you can improve quickly.

Page Settings

Page Setting is important because it lets you test the page loading times with different software and networks. Make sure you opt for fast loading times on Firefox, Safari, Chrome and Opera (the most common browsers).

Monitoring And Alerts

If your site is hosted by someone else, they likely don’t care about your site’s load time as much as you do. Perhaps they will notify you when outages occur (and perhaps they won’t), but what about when their servers are malfunctioning or running slow?

Monitoring allows you to set conditions under which you’ll be alerted. Good alerts to include are major increases in site load time or site traffic.


The Waterfall chart summarizes the impact of each feature of your site on the site’s load time.


Timings gives you even more information, including the Time to First Byte (TTFB) metric which is important because it’s the time between a user sending a request to your site, and when they receive a response.

Another important statistic is first paint time, which describes the time between the user’s request and when your site’s visual elements are displayed.


The Video tab lets you record a video of your page as it loads.  You can slow it down and look at the telemetry to find the causes of hangups.


History gives you a record of your site’s loading speed over time.


PageSpeed and YSlow

PageSpeed and YSlow perform similar functions, with PageSpeed measuring Google’s metrics, and YSlow looking at Yahoo.

For some people, PageSpeed will be the obvious choice because it can be used alongside other Google tools that are essential to maintaining the performance of a website, such as Google Analytics. However, you might find that YSlow is more developed because it has been around much longer and the web page analysis it offers is based on 23 testable rules.


PageSpeed is Google’s metric which measures site loading times, so it carries a lot of weight.

You will see a list of suggestions at the top of the page. There are many things that could be slowing down your page – work through the list, starting with the priority listings.

If you’re not sure how to implement PageSpeed’s suggestions, check out this link.


YSlow is composed of 23 separate metrics with which it tests your site.

YSlow gives you a list of criteria and scores your site, just like PageSpeed. You’ll probably find that a few of the metrics overlap between PageSpeed and YSlow.

If you’re not sure how to implement YSlow’s suggestions, these resources could help you.

Get the best out of GTmetrix

Make sure that you utilise the “What’s this mean?” button, and avail yourself of the entire library of information GTmetrix has about its functionality. Its pretty easy to forget what an advisory means, or how to fix it.

GTmetrix is just one of the programs available for site testing, but it is a very valuable tool in the web designers arsenal.

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