Just How Useful is Google Lighthouse?

Google2.0.0What Is Google Lighthouse?

Google has long been the authority on best practice methods when it comes to SEO. Over the years, they have expanded their role from an impartial search tool, to a provider of services that complement their own engine, such as Google Ads, Google Recommendations, web and email hosting, GSuite Apps, etc. All tools we know and love.

So it stands to reason that a lot folks are rightly concerned with how Google evaluates the performance of their website, even if that doesn’t necessarily translate to a better front end user experience for customers. For a time, Good Page Speed insights was an up and coming tool that people used to cater to what Google thinks is important. This could be anything from how scripts are rendered on a page to how images are optimised for various screen sizes. However, due to a lot of inconsistencies and confusing results, especially for the every day user, Google evolved this into a tool called Google Lighthouse. This tool is essentially a theoretical user experience test, so it isn’t strictly a performance evaluation and should be interpreted with a grain of salt.

While it’s generally a good idea to optimise the performance of your website, chasing a good grade alone will not always provide the best result.

If you are currently using Page Speed Insights to evaluate your website, I’d highly recommend using Google Lighthouse instead, as it is more future proof and currently the tool that Google themselves are more invested in. Other tools like GTMetrix and Pingdom Tools will give you a great second and third opinion as well, and focus more on the speed and performance of your site. When using these, be sure to set your location to Australia or where your primary audience is for accurate results.

How To Use It Correctly

Because Google Lighthouse actually runs on your local computer, it can be more accurate in providing real-world results, but it can give incorrect readings if you’ve got a lot running on your computer. The main thing to keep an eye on are which extensions are enabled, as these can actually impact the results significantly. The easiest and quickest way around this is to run the tool in an Incognito window in Chrome.

So to get there, follow these steps to run your first test:

  1. Open Chrome.
  2. In the options, open Chrome Devoper Tools
  3. Select the “Audit” tab.
  4. Select the device type that receives the most traffic. In most cases, people view sites on their smartphones/mobile now.
  5. Tick all options for the audit to get the full report.
  6. Run the audit.
  7. Don’t click or do anything while the test is underway for more accurate results.

Your screen should look something like below before running the test (although my version has a darker background):

Chrome Dev Tools Google Lighthouse

Viewing the Results

When you finish running the test, you should see a report that lists a number of improvements that can be made. Again, not all of these may be relevant, but I particularly take note of the “Performance” metric, as in my experience it relates the most relevant info in helping improve the user experience of the website.

So you can see the difference, I ran the same test via my normal browsing window and incognito. You can see the massive difference below:

Lighthouse Without Extensions
Using an Incognito window
Lighthouse With Extensions
Using a normal browsing window

What to do when issues are detected on your website

We’ve had a good number of clients ask us what certain notifications mean, for example, “Defer parsing of Javascript” or “Fix Mobile Usability Elements”. Some of these are super helpful while others are a bit misleading, so it’s always a good idea to send them to your web developer, or me, to interpret the results. Remember, this tool is really meant for developers, so not every warning or notice is necessarily negative, and in some cases can be a false positive without further testing.

In any case, it should give you a good idea on what could use some improvement, which is the first step to improving your website experience. Whenever you come across these messages, it is usually best to forward them to the person that manages your site, or get in touch with me to check it out.