Optimization faq

Why does site performance matter?

Shopify prioritizes site speed optimization for merchants, and for good reason. Site speed can be an indicator of how your site is performing overall. Speed scores are generated by services like Google PageSpeed Insights, which weigh several factors that affect load times on your site. 

Site speed also impacts Google rankings, user experience, and ultimately conversion rates. A 1-second delay in page load time has been found to yield 11% fewer page views, 16% decrease in customer satisfaction, and a 7% loss in conversion. Even Walmart backs up this data: in a study, they found that every 1 second of speed improvement led to a 2% increase in conversions.

Optimizing your online store speed can improve the shopping experience for your customers, make your store more discoverable, and increase conversion. Learn how your store performs against industry standards and other Shopify stores like yours by viewing your Online store speed report.

 

How does theme speed factor into overall site speed?

Overall, site speed is dictated by two main factors: server-side efforts and client-side efforts. Shopify will handle the server-side efforts for your website, so the most impactful thing you can do to improve your site speed is to look critically at your theme. Page rendering times (how quickly the page displays) can be largely affected by the structure of your theme.

Themes developed by Shopify are already optimized for site speed. They render quickly and prioritize minimizing the amount of data required to display the page. Adding functionalities to themes can improve the overall brand image, but can often impact the performance of the theme. When modifying your theme or adding apps for greater functionality, each addition should be reviewed carefully to ensure that the performance trade-off doesn’t negatively impact the shopper experience. 

 

What does Shopify do to improve page speed?

To ensure server-side performance, Shopify adopts the following tactics. 

Browser caching

When you visit a website, the elements on the page are stored on your hard drive in a cache, or temporary storage. The next time you visit the site, your browser can load the page without having to send another HTTP request to the server.

 We set our browser caching for resources hosted on your store (JS and CSS files, image files, media files, PDFs) to one year for each file – the maximum possible.

Content delivery network 

Shopify provides all merchants with a world class Content Delivery Network (CDN) at no additional charge. A CDN is a collection of web servers distributed across multiple locations to deliver content more efficiently to users. This means that your shop will be fast regardless of where your buyer is located. Our CDN serves up all assets using HTTP/2. This reduces overhead by using a single TCP connection with multiplexed streams, instead of opening up several connections simultaneously.

Gzip compression

As web pages become more complex, they also become bulky and slow to download. The best way to speed their load time is to compress them using a technique called Gzip. Gzipping reduces the bandwidth of your pages, thereby reducing HTTP response.

Shopify employs this compression technique on CSS, JavaScript, any documents (for example, PDFs), and the page itself. We also enable keep-alive, which allows the browser to grab more than one file at a time.

Image optimization

Shopify automatically optimizes your images through our compression algorithm. Keeping image sizes to a minimum can help users on slow connections. For supported browsers, Shopify will automatically serve up your images in WebP format, which is up to 30% smaller than traditional image formats.

Note:  In order to minimize quality losses during compression, save your images in the proper format and size from your graphics program. We recommend viewing Theme Images documentation, particularly the Formats section, which covers proper use of JPG, PNG files, and compression rates.