You may be wondering why you're not getting 80 or 90 out of 100 for your page speed. You may be seeing a score more like 20 and think "Why is this so low? Is this the theme? Apps? My content? This sounds bad - I don't want my customers to turn away and I don't want to be penalised in search rankings."
Let's run through how this speed is calculated, what it should be, what its effects are, and how to improve it.
How is it calculated?
Shopify uses Google's Lighthouse test suite, using the 'Mobile' profile.
Google have a page that explains how to run this yourself: https://developers.google.com/web/tools/lighthouse/
Shopify runs the same report, but averages it out over a period of time to get a more accurate score.
When this runs on a Shopify site (using our Symmetry theme's Duke demo store as an example), it gives you a report like this:
What should it be scoring?
Our demo store score is red! It's under 50! Should we be panicking?
No! We're very happy with this. We don't want to pick on any stores, but here are some examples:
Amazon - 26
mvmt.com - 17
gymshark - 6
apple.com - 32
Google's own Lighthouse documentation page - 11
There is clearly no correlation between success and this page speed score.
That's really the bottom line. Unless it's actually taking 5-10 seconds to show something on a real computer - you're fine.
I will, however, continue to explain why it is very unlikely you can have a high score on Shopify. Just in case you fancy reading a bit more about this.
There are some things on the store that are necessary to how it runs, and lowers this score. Things Shopify load in so that payment buttons work, and you can monitor customer sessions and behaviour. If we cut these out, the score goes up to this:
But these cannot be cut out - you need them for your store to work! A simple blog doesn't need this, but an online shop does. You should be very comfortable with anything around 20 and above, if it feels OK on a real device.
It's worth noting that (with Shopify's tracking put back in) the total page download here was 332kb, and is interactive in 511ms on my 7 year old desktop computer, with a pretty average internet connection (which still cuts out during video chats 🙄). This is really good! Well above recommended/average results for a website.
We don't want to boast (too much), but check this same Duke demo store home page out when we run it in the 'Desktop' profile:
That's great! That's a speed on par with google.com - one of the fastest pages on the web. There's no real room for improvement here.
If you want to know what to aim for, try running it on a demo store for your theme. You'll see what a store without modifications will give you. We also put a lot of content on demo store home pages to show off what the themes can do, including lots of detailed images, often with videos and maps, and usually include Shopify's reviews app, all of these will lower the score a little.
You should be able to get a score that is similar to our demo stores, with the right content and without a lot of apps.
What are the effects of speed on search rankings
Here's a useful video from Google about SEO that mentions page speed: https://www.youtube.com/watch?v=XUOD6pcvnso
In summary, it doesn't have a strong effect on rankings. Google may penalise super-slow stores a little bit, but the content is factored in way more than speed ever will, and if you're above a certain "this site is so slow it's unusable" threshold additional tweaks will not have an effect.
How to improve this speed score
The first thing to do is just load up your store on a real device. Does it feel fast? Many stores with low scores feel pretty fast to me, even on my phone with WiFi disabled. This score is artificial, and not an actual indication of how fast it loads on a real device. If it feels good, and doesn't feel noticeably slower than your competitors, then there are probably better things to spend your time on than increasing this page speed score.
If you still want to improve the score, the number one thing to do is remove apps that affect your web pages. Here's a good evidence-based assessment of how apps bring a score down: https://speedboostr.com/how-apps-affect-load-speed/
Note: Apps that don't affect your pages won't affect your score in any way. For example, order printing apps, or apps that sync your customer list to mailing lists.
If you have no customisations in the theme, and only a few apps that you absolutely need, and the score still seems a little low, then here are some options:
1. Put less on the page - for example, include fewer product rows on the home page - these take time to render and serve to customers.
2. Make sure you are using jpg images - png images are much larger and cannot be compressed as well as jpgs.
3. Update to the latest copy of the theme. We may have included some optimisations to speed up the theme a little, and it will ensure there won't be any lingering code from apps you have uninstalled in the past. See here for more information about that process: https://support.cleancanvas.co.uk/hc/en-us/articles/360007222898-Updating-your-theme
I hope this helps clarify a few things about page speed. Limit your apps, use jpgs, and don't be too worried if it seems low - if it's in double figures you're probably OK!