Why Is My BigCommerce Store So Slow

How to fix it

Try these in order — the most common fix is first.

1. 1. Measure by template

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   1. Run Lighthouse on home, category, product and cart pages separately
   2. Note the biggest scripts and images in each
   Did this fix it? Yes No

2. 2. Clean up scripts

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   1. Open Storefront > Script Manager and remove unused tags
   2. Search theme files for leftover code from uninstalled apps
   3. Defer non-critical third-party scripts
   Did this fix it? Yes No

3. 3. Optimize images

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   1. Resize product images to the displayed size
   2. Use compressed formats
   3. Avoid lazy-loading the main product image above the fold
   Did this fix it? Yes No

4. 4. Update the theme

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   1. Update Stencil theme to the latest release
   2. Remove unused carousels and libraries
   3. Test changes on a duplicate store or preview theme
   Did this fix it? Yes No

Symptoms

Slow page loads, poor Core Web Vitals or low Lighthouse scores on mobile.

Why it happens

• Large unoptimized images
• Scripts left behind by removed apps
• Third-party tracking and chat widgets
• Custom Stencil overrides and plugins
• Outdated theme

This guide also covers

• bigcommerce slow
• why is bigcommerce so slow
• bigcommerce page speed

The same problem in other apps

All slow, laggy or resource-hungry guides →

• Why Is My Shopify Store So Slow (Shopify)
• Why Is WooCommerce So Slow (WooCommerce)
• Why Is My Squarespace Site So Slow (Squarespace)
• Why Is My Wix Site So Slow? (Wix)

Other BigCommerce errors

• BigCommerce Checkout Not Working
• BigCommerce Payment Gateway Error
• BigCommerce Forced Plan Upgrade (Sales Limit)
• BigCommerce Open Payment Provider Fee
• BigCommerce SSL Certificate Not Working
• BigCommerce Custom Domain Not Working
• BigCommerce Product CSV Import Errors
• BigCommerce Out of Delivery Zone Error at Checkout