A theme decides how fast your store feels and how much of your time it eats. Most rankings are screenshots in a list. Ours are measurements: every theme installed on one store, with the same products and the same images, and timed the same way.
The theme guides
What we measure, and why those three numbers
Three figures decide whether a theme is fast in a way a shopper would notice. LCP is how long until the main product image is actually on screen — the moment the page stops feeling broken. CLS is how much the layout jumps while loading, which is what makes people tap the wrong thing. Page weight is how much has to come down the wire, and it is the number that decides all of this on a phone on mobile data.
Everything is measured on a development store with [12] products, [4] images each, and no apps installed. Apps are the single biggest thing people do to their own load times, so measuring a theme with apps installed measures the apps.
The part nobody says out loud
Price and speed are not the same axis. Shopify’s own free themes are built by the same people who build the platform and are not the slow option by default; what money buys you in a premium theme is sections, layout control and someone to email when something breaks. Whether a given paid theme is faster than a given free one is a question for the measurements, not for the price tag — which is the whole reason we take them.
The second thing worth knowing before you buy: what a page builder app creates usually does not survive a theme change, while your products, orders and customers always do. That asymmetry should shape how much you build outside the theme itself.
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