Content personalization works based on our live audience segmentation. When you create a new segment for your audiences, we start evaluating shoppers against the criteria and place them in segments.
Content personalization campaigns (both Image and HTML) are fetched and cached once a shopper lands on your website. Afterwards, our live segmentation keeps updating on each new page view and based on the segment that applies to the shopper, appropriate content personalization campaigns personalize the page based on the campaign's placements and configuration settings in our Designer.
We use the "cloaking" mechanism to update content on your site. To learn more about this in detail, click on this article for more info.
Affect on Site Speed
Content personalization dynamically changes some HTML elements directly in the browser. It doesn't create new pages on the server and it doesn't create new URLs. That means that search engines mostly see the unaltered version of each page whereas individual users see different versions of the same page as it's changed on-the-fly in their browser.
When you use an Image Content Personalization campaign, several URLs with different sizes are created for your images and all version are hosted on fast Content Delivery Network (CDN). The browser makes the decision to download only the one size that is best suited for the user based on what area of the page it occupies, device display type, etc.
Images delivered through our CDN can be cached in the browser for faster load times.
If multiple campaigns that target the same element on the page apply to the same user through different audience segments, the Precedence set on the audiences applies and the content will be personalized only based on the audience segment with the highest precedence (lower index on the list). That means that no unnecessary data is transferred on the network for any images that will not be used.