I tested how much Shopify page builders actually slow down your store ,Here are the numbers
So, when you add a page builder to a clean Shopify theme, in my tests they added roughly 260 KB to 350 KB of extra page weight and increased LCP by around 0.25 to 0.60 seconds on mobile.
Here is the raw breakdown from my tests:
• PageFly: +350 KB added | 5 scripts | +300ms to +600ms LCP increase
• GemPages: +330 KB added | 4 scripts | +300ms to +550ms LCP increase
• Zipify: +290 KB added | 3 scripts | +250ms to +450ms LCP increase
• LayoutHub: +260 KB added | 2 scripts | +200ms to +400ms LCP increase
It was a bit surprising that PageFly had the heaviest overall impact. It loaded 5 separate builder-related scripts in my test.
*How I tested it:*
• Baseline: Clean, default Shopify Dawn theme with zero extra apps, tracking pixels, or chat widgets.
• Test Page: Built the exact same landing page on all 4 apps (1 banner image, 3 feature icons, a 4-product grid, and 1 review block).
• Setup: Tested using WebPageTest on a standard mobile connection . Ran 10 tests per app and took the averages.
And the most important thing these results are from my specific test setup, so they shouldn't be treated as universal numbers for every Shopify store.
If you're using page builders for your main landing pages, are you seeing similar drops in mobile speed, or have you found good ways to defer their scripts?