lightbulb_outline Blog Post: Fast ads matter (web.dev)

Load tags only once per frame

Overview

This audit ensures that no frames load the same ad tag library script more than once. Including the same script multiple times is unnecessary and can lead to decreased page performance.

Recommendations

Remove duplicate ad tag library scripts. In some cases, duplicate scripts can be unknowingly loaded from two different locations. Examine where each duplicate script is coming from by reviewing network traffic and grouping requests by frame.

Identify the source of duplicate scripts

Use the Network tab in Chrome DevTools to determine which frame is loading duplicate scripts.

  1. Open DevTools by pressing Control+Shift+J or Command+Option+J (Mac).
  2. Navigate to the Network tab.
  3. If not already visible, click Filter The Filter icon to open the filter bar and select JS.
  4. Open Network Settings The Network Settings icon and select Group by frame.
  5. Reload the page to capture network traffic.

A screenshot of the Network tab in Chrome DevTools

More information

The following ad tag library scripts are supported:

Library Script(s)
AdSense

pagead2.googlesyndication.com/pagead/js/adsbygoogle.js

pagead2.googlesyndication.com/pagead/js/show_ads.js

Google Publisher Tag

googletagservices.com/tag/js/gpt.js

securepubads.g.doubleclick.net/tag/js/gpt.js