Check 4 / 12 LOW impact In the full checklist
Defer non-critical JS: reviews, chat until interact
What this check is
Review widgets and chat bubbles are heavy and irrelevant to the first screen. Deferring them until the shopper scrolls or interacts keeps the main thread free for the buying path.
How to implement it
Load chat and review scripts on first scroll, tap or idle timeout, and make sure the deferred widget does not push content when it finally renders: reserve its height in the layout. Verify the deferred code does not block the add-to-cart interaction.
How to verify it
Record a mobile trace and confirm no third-party review or chat script runs during the first seconds, then scroll and confirm the widget loads without a layout shift.
All 197 checks, one Google Sheet
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