Case study: How Google Tag Manager and Wistia impact site speed
Recently, we noticed that our new website TopLine Film was loading unusually slowly. So, we investigated and solved the problem (with some help from top WordPress design team Highscore). Sharing is caring, and even though we rate ourselves as an SEO agency we still love a school day and thought we’d share what we did from start to finish, in the hope it might help some of you kind folk.
Identifying the problem
We ran tests on the website without Google Tag Manager and Wistia, and the load speed times significantly improved.
Changes to Google Tag Manager and Wistia
First, we added inline versions of the tags contained within Tag Manager and simply stopped using it as a container.
Wistia was a bit more difficult because, while we needed to reduce the number of Wistia requests on the site, we still needed to use it to show off our video work. So, we condensed the number of Wistia videos to three per page on desktop (some pages, including the homepage, had originally carried a lot more).
For our mobile site, we completely removed onpage videos and instead created a call to action box, linking to our main work page (where all the videos could be found).
Before the updates, the speed score was (a rather slow) 34:
After the updates were made, the speed score on mobile more than doubled to 73 (the higher end of average):
Removing Tag Manager and associated tags resulted in a PageSpeed Insights score jump from 34 to 56 – 22 points (the difference between ‘Slow’ and ‘Average’ in Google’s eyes). We then removed the Wistia videos altogether from the homepage and instead replaced them with a call to action directing users to the ‘Our work’ page containing all of the videos – this resulted in a further 17 point jump (to 73)!