How to use this guide
Open the failing metric’s section and work through those tutorials in order.
How to action
Run a diagnoisis of your store here:
Work the section that matches the metric you are failing. Skip the rest until that metric is in range.
- Failing LCP → LCP (slow images / videos)
- Failing FCP → FCP (slow display)
- Failing INP → INP (slow tap / lag)
Do the tutorials in that section in order. Re-run the report after each change so you know what actually moved.
Dev resources
This is to help whoever implements the fixes
- Find assets in your code → Finding assets in the code
Testing
ALWAYS CREATE A DRAFT THEME
ALWAYS TEST BEFORE AND AFTER
You always want to check the before vs after when implementing this work. Site speed is a very nuanced field, and best practices on some sites, will not work on others. There are 3 ways to test, with different levels of completeness
- Google Developer Tools → (fastest, but complex)
- Fastersite.ai → (comprehensive, but slow)
- Google Page Speed → (slowest, but most detailed)
When testing before x after, use your your draft theme URL, or your local Shopify CLI url to test against the live site.
Using AI
I've tested these secetions indivdually using cursor + my Shopify code. You can copy + paste the link to any guide in your IDE and ask it to implement.
Check the code before any of it goes live, but for the most part - this will work.
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