Welcome to Shopify Theme Basics! Here at Fluorescent, we’re Shopify theme experts. In this series, we’re sharing our knowledge with you. This is our second instalment and goes over everything you need to know about store speed. Let’s dive in!

Why is store speed important?

Your store’s speed and performance are essential to a smooth shopping experience. If your site is noticeably slow, customers may get impatient and leave, or key features may not work as expected.

Performance also affects accessibility. A well-performing site ensures all customers—whether they’re on older devices, slower connections, or using assistive technology—can shop with ease and enjoy all that your store offers.

Store speed may also influence your search ranking. While the quality of your content is the main factor, reliable site performance can give you an edge over competitors with similar content.

However, it's important to remember that speed is one part of your store’s successful performance. Focusing on store speed can make it feel like you’re in a race, when it’s not really about being the fastest—it’s about providing a reliable, accessible, and enjoyable experience.

How do I find out my store speed?

There are many tools to measure site speed, but Shopify's Web Performance dashboard gives the most relevant insight for your store. In your Shopify admin, on the Themes page, you’ll find metrics and rankings for Core Web Vitals, along with detailed reports of your store’s performance.

We’ll explore Shopify’s speed tools in a later article. For now, you can learn more in Shopify’s Web Performance guide.

What is considered a good speed?

Shopify ranks page loading speeds of around 2.5 seconds as “good," whereas “poor” is more than 4 seconds. However, a rank below “good” doesn’t necessarily mean your store needs fixing. Speed and performance come down to quality rather than quantity. A good store speed delivers a smooth, high-quality shopping experience for actual visitors. A poor store speed visibly affects how your store loads and performs.

Technically, a near-perfect speed score is possible—if you strip your site to just text, but that’s not realistic for stores. Sites with more quality content and features will naturally have a slower speed rank, but often the difference in load times will be imperceptible.

When evaluating your store’s load times, you might want to keep in mind that the average human blink lasts 100 to 400 milliseconds.

Also, be aware that some speed tools can be misleading because they don’t take into account the real user experience. For example, animations may be flagged as delays, even though they run after a page has fully loaded and enhance the user experience.

If you’re concerned about a low store speed, review your site page by page. Test on different devices or browsers, and look for specific areas where things feel slow or don’t work as expected.

What factors impact my store’s speed?

There’s a lot that goes into your store’s performance, including Shopify’s infrastructure, your customer’s device and connection, and store features.

Most changes to your storefront will technically impact load times, even if it’s microscopic, like when you add more products to a page or more features and content. Other changes, like adding long autoplay videos or custom code, or installing apps can have larger impacts.

What does my theme have to do with my store’s speed?

Shopify ensures that themes do a lot to optimize your store speed. All themes sold in the Theme Store are held to Shopify’s code and performance standards. At Fluorescent, during development, we run our themes through a gamut of tests to ensure top performance across browsers, devices, and connection speeds.

For example, themes automatically display the optimal image size depending on the customer's device. Many themes also use "lazy-loading" to load content and resources only when needed, as visitors scroll down the page.

Performance standards change and it’s important to keep your theme updated. We recommend checking your theme’s changelog for the latest theme version.

Shopify's Theme Comparison Chart shows the speed scores for each theme sold in the Shopify Theme Store (as of 2024 - some newer themes are not listed).

What can I do to speed up my store?

There are a few things you can do to help improve your store speed. Start with small, gradual changes to your store. You don’t want to do anything drastic that will change the quality of your store—remember that it’s all about striking a healthy balance between technical performance and user experience.

Resize images and reduce autoplay videos. For sections with autoplay videos, we suggest a maximum limit of 10mb or about 10 seconds. Effective autoplay videos are short and concise.

Remove unnecessary apps. Both third-party app code and the total number of apps will increase page load times, sometimes significantly. Always weigh the benefits of an app against the cost of speed (does it contribute to your bottom line?).

Use default fonts. Shopify's font picker supports hundreds of great fonts that load faster than custom fonts. If you are using custom fonts, consider using system fonts.

Speed up your homepage. Consider reducing the number of images on the homepage and/or using curated collections to feature smaller numbers of products on the homepage.

Review custom code. Custom code can also come at a cost, so we again recommend making smaller gradual changes. Make sure code customizations are still necessary; the latest theme version may support some features you want.

Turn off unnecessary features. There are some features that are "heavy" and will have a larger impact on speed. For example, disabling Shopify's Dynamic "Buy now" button can increase product page speed but at the cost of your conversion rate. This is a situation in which you'll want to balance page speed vs. user experience.

What if having lots of images and videos is good for my brand? Should I delete them all in order to speed up my store?

Before you do anything drastic, make sure your images and videos are appropriately sized.

• If you have an image that’s 5000 px wide used for a small image block, resize that image to get closer to the max width of that block.

• Trim autoplay videos down to 5 seconds long.

• For slideshows, avoid having more than 3 slides (visitors are unlikely to click through lots of slides).

If you're concerned about the size of your images, check out Shopify's 8 Tips for Image Optimization.

What do all these acronyms mean? LCP, CLS, INP

These are all useful acronyms to know when learning about store speed:

• LCP - Largest Contentful Paint measures how fast the largest element on the page loads. LCP corresponds to your store’s “Loading speed” metric. Slow LCP scores are often related to elements like autoplay videos.

• CLS - Cumulative Layout Shift tracks how much page content moves unexpectedly while loading. Sometimes shifts can frustrate user experience, like having a button move when you’re about to click it. Note that some speed tools trigger false CLS warnings for elements that are meant to shift, like slideshows, popups, or animations.

• INP - Interaction to Next Paint measures how long it takes the page to respond to user interaction (e.g. clicking a button). Poor INP scores can be a result of too much custom JavaScript or app code.

What metrics are the most important? How often should I test them?

Shopify’s built-in Web Performance tool tracks LCP, CLS, and INP. These metrics are the most important because they can have the most likely impact on real user experience.

If you notice a ranking of “moderate” or “poor”, you’ll want to use Shopify’s web performance tool to investigate. Improving store speed can be a complex task, so you may wish to hire expert help (check out our Partner Directory for businesses that could be of assistance).

That’s everything you need to know about store speed! Check back for more Shopify Theme Basics coming soon.

How else can we help?

At Fluorescent, we love building relationships with our customers! We’re here to support your business and help you grow.

If you are…

…already using one of our themes and need some assistance, head over to our documentation.

…looking for a speedy new theme, check out our themes Eclipse, Stiletto, and Cornerstone.

…an agency or freelancer, read about our partner program and how it can help grow your business.