Measuring can be tricky. One needs tools to do the job right, and there is no shortage of options out there.

Table of Contents

• You have to start by measuring
• Why does measuring matter so much?
• Enough already, give me the tools
• Ok, I measured, what now?

You have to start by measuring

When approaching performance, you need to start with profiling. The first thing you want to do is identifying the problem: finding what’s wrong is always the first step of making it right. That’s why measuring is so important when it comes to page load performance, if you don’t have metrics to compare, you don’t have a measure of success. You can’t just rely on "it feels faster", you need data.

Why does measuring matter so much?

The more I work on performance, the more I realize the real importance of having measurements to refer to. Everytime I approach a problem without a proper metric, I end up tweaking in the wrong places of the project. I learned the hard way that you have to always start with profiling.

Two things happen for free from the moment you have proper data to work with:

• You start actively working in the right places, meaning you are able to attack right at the root of the problem
• You immediately notice regressions. So many times I fixed something, only to introduce the problem back an hour later without even noticing

That’s why a proper performance based strategy heavily relies on continuous assessment. You want to set a clear performance budget, meaning the constraints your website is expected to meet, you want to gather relevant metrics every time you make a change, and compare those with your budget.

Enough already, give me the tools

Measuring can be tricky. One needs tools to do the job right, and there is no shortage of options out there. Here are the best free tools I recommend to measure the performance of your site. Each of them with unique features, measurements and reporting.

Google PageSpeed Insights

For a long time, Google PageSpeed Insights has played the role of uncontested king of performance measurement tools. It owes its popularity due to three fundamental characteristics:

• It's provided and sponsored by Google
• It gives your site a simple score between 1 and 100, which makes it very easy to digest
• It automatically suggests what steps you should take to increase your score to 100

One great thing about this tool is that its reports aren't detailed and full of technical jargon.

Test My Site With Google

More recently, Google has published this new tool, which performs similar tests, yet with a specific focus on mobile. It generates a free report and will give you a very interesting comparison between you and the industry average

Pingdom Speed Test

Pingdom is one of the most known speed test tools. This one generates a highly technical dissection of your website, including the page’s Google PageSpeed performance grade, a waterfall breakdown of the network requests, the overall page size, a breakdown of the content by type (images, scripts, HTML, CSS, and so on).

It includes also some performance insights, meaning tips to make your website faster.

Yellow Lab Tools

Yellow Lab Tools is a simple yet powerful one. You can pick the device type you want the test to be run on (desktop, tablet or phone), and you'll get a complete breakdown of your page.

Notable sections of the report are: Scroll bottlenecks, Bad Javascript, Web fonts and Server config.

WebPageTest

WebPageTest is my personal tool of choice. It’s target are developers and technical managers, therefore it may not be the most accessible of this list, however it gives you more information than you could ever need.

What's especially useful about this tool is that it tests your website on real devices. It can run speed test from multiple locations around the globe, using real browsers and at real consumer connection speeds (quoting the homepage here). Not only you can choose device, browser and connectivity conditions. You also get awesome performance reporting as a result: a film view of what got painted and at what point in time, a breakdown of the network requests, a JavaScript timeline, plus a ton more of information.

Ok, I measured, now what?

Measuring is just half of the journey though. You should probably know your metrics, and have an auditing process. Feel free to steal mine at I Want To Audit The Performance Of My Website, Where Do I Start?