Where it costs money directly.
WHY IT MATTERS MORE
A slow homepage loses visitors. A slow checkout loses sales that were already won.
WHAT TO PRIORITISE
The checkout path, above everything Product pages Category pages
WHAT MAKES SHOPS SLOW
Product images, in volume Category pages showing too many products Cart and checkout pages, which cannot be cached Plugins adding queries per product Related products and cross-sell queries
FOR CATEGORY PAGES
Show twenty products, not a hundred. Nobody scrolls that far and it costs loading time.
FOR THE CHECKOUT
Cannot be cached. That makes everything else about it matter more.
Remove unnecessary scripts from it. Test it on mobile data specifically.
FOR PRODUCT IMAGES
Standardise size and compression. Apply on upload.
WHAT TO TEST REGULARLY
Complete a purchase on your phone on mobile data.
That is the experience that determines your revenue.
