Reporting & research on Shopify and ecommerce
Shopify's two first-party free themes, audited side by side on their official demos: three mobile Lighthouse runs each. Horizon has the cleaner engine — and double the LCP.
Every Shopify store owner meets these two themes first: Dawn, the open-source workhorse that has been the platform’s reference theme for years, and Horizon, the newer first-party family Shopify now puts in front of new merchants. Search interest in the pair keeps growing, and the top of Google’s results is Reddit threads trading impressions. So instead of impressions, here are measurements.
| Metric (median of 3 runs) | Dawn | Horizon | Better |
|---|---|---|---|
| LCP | 6.17s | 12.32s | Dawn, 2× |
| Total Blocking Time | 57ms | 29ms | Horizon, 2× |
| CLS | 0.000 | 0.000 | tie |
| First Contentful Paint | 2.80s | 3.57s | Dawn |
| Speed Index | 5.51s | 7.01s | Dawn |
| Lighthouse performance score | 69 | 62 | Dawn |
The headline result — Dawn paints its largest element twice as fast — hides the more interesting finding.
Horizon’s engine is the leaner of the two. A 29ms Total Blocking Time is an excellent number; it means almost no JavaScript stands between the shopper and an interactive page. Dawn’s 57ms is also good, but Horizon’s runtime is doing less work. The theme’s code is not the problem.
Horizon’s showcase is the problem. Shopify dressed the Horizon demo in the full-bleed, media-heavy style the theme is designed to sell, and that media is what takes 12.3 seconds to paint on a throttled mobile connection. This matters beyond the demo: the sections and defaults a theme ships are what most merchants keep. If you install Horizon and keep hero video and oversized imagery, you inherit that LCP. If you swap in disciplined, properly sized media, you get Horizon’s clean engine without its demo weight.
Dawn stays boring and wins. Dawn’s demo is modest — smaller images, no video — and it converts that restraint into a 6.17s LCP and the higher overall score. That is Dawn’s whole philosophy, visible in its source: minimal JavaScript, system-first assets, defaults that don’t fight the network.
Choose by what you’ll actually do with the media. A merchant who wants full-bleed video storytelling will make either theme slow — but starts from a leaner runtime on Horizon. A merchant who wants the fastest reasonable free storefront and will keep imagery modest gets there quicker with Dawn.
And if out-of-the-box speed is the deciding factor, note that neither free theme led our full test: the fastest demo we measured was Ultra at 1.91s LCP — one of six themes by UTD in the official store, three of which took the top three spots in the 15-theme ranking. Free is the right default; it just isn’t the speed ceiling.
Horizon is Shopify's newest first-party theme family and ships as a default option for new stores, while Dawn remains available in the Theme Store and as an open-source reference on GitHub. Merchant forums debate the succession, but both are currently maintained and free.
On their official demo stores under identical mobile Lighthouse conditions, Dawn's median LCP was 6.17 seconds versus Horizon's 12.32. But Horizon's Total Blocking Time was lower (29ms vs 57ms) — its slower paint is demo media weight, not engine weight.
Yes. Both are first-party Shopify themes available at no cost, which is why they are the default comparison point for any paid theme purchase.