Lazy Loading
Last edited: 2024/05/28
Lazy loading pauses requesting and rendering ads until they approach the user's viewport.
So far Lazy Loading is part of 
Prebid Stack. It will be migrated to Viewability Tools module in New Platform.
Prebid Stack. It will be migrated to Viewability Tools module in New Platform.Within Viewability Tools, you can use one of the Lazy Loading technologies:
- Yieldbird’s lazy load (recommended, can be enabled and disabled on ad unit level)
- Google Ad Manager’s lazy load (can be enabled only on the entire domain)
Google documentation on lazy loading: GPT documentation
Attention: When you use Viewability Tools’ lazy loading, you shall not use 
Ad units detection & targeting mode set to
Ad units detection & targeting mode set to Detect ad units on page load and lazy load targetingYieldbird’s lazy loading vs Google Lazy loading comparison
Yieldbird’s lazy loading | Google lazy loading | |
Configurable per ad unit | yes | no |
Configuration
Regardless of whether you choose Yieldbird’s or Google’s lazy load you can configure the same parameters:
- Auction Margin Percent (available only when using Yieldbird’s
Prebid Stack) The distance between the user's current viewport and the ad slot at which the Prebid auction is triggered. e.g. 100 = call Prebid auction within 1 viewport, 200, within 2 viewports etc.
- Fetch Margin Percent The distance between the user's current viewport and the ad slot at which the ad slot sends ad request to Google Ad Manager. e.g. 100 = fetch slots within 1 viewport, 200 = within 2 viewports etc.
- Render Margin Percent The distance between the user's current viewport and the ad slot at which the ad is rendered. e.g. 100 = render slots within 1 viewport, 200 = within 2 viewports etc.
- Mobile Scaling Multiplier for the three above parameters that apply to Mobile devices. e.g. 2.0 means that the three above parameters will be doubled for mobile devices (e.g. if you set render margin percent to 300, for Mobile it will be 600).
It is recommended to set render margin lower than fetch margin
It is recommended to set Mobile Scaling higher than 1 (e.g. 2) because generally Mobile viewports are smaller and users are scrolling faster than on Desktop.
Should I remove my own GPT lazy loading setup to use Viewability Tools' Lazy Loading?
Attention:
You must remove all existing scripts that handle lazy loading before using either GPT lazy loading or Yieldbird's lazy loading in Viewability Tools. If you do not, it may result in lazy loading not functioning properly or being activated twice.