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

Initial investigation using Google’s PageSpeed Insights tool revealed that this issue was being caused by a combination of too many large images and problems with hefty JavaScript requests.

The two main JavaScript culprits were Google Tag Manager and Wistia (a video hosting platform).

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).

Desktop results for TopLine Film

Before the updates, the speed score was 79 (the top end of average):

After the updates, the speed score:

Mobile results for TopLine Film

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)!

While the principle of Tag Manager is great (who wants to be stuck in a dev queue for six months after all?), we’ve learnt it’s important to test the impact of tags as you add them and ultimately be prepared to remove Tag Manager altogether if speed is paramount (it is a ranking factor after all and slow sites kill conversion rates). We’ve also learnt to consider what else happens as the source code is rendered into a DOM – as JavaScript modifications (like video loading) can seriously slow down your mobile performance. 

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