This is the documentation for Performance Edge. If you'd like access, please reach out to your Optimizely account manager.

Optimizely Performance Edge is a faster way to deliver client-side web experiments that takes advantage of a distributed network called "the edge." Performance Edge is designed to improve page performance by performing targeting and variation assignment tasks at the Edge instead of in the browser.

You have a unique Optimizely endpoint available to you at the Edge. It not only buckets your users into experiments and variations, but also returns only the changes needed to power those experiments and variations on the current page. Asynchronously, it also loads an Optimizely tracking snippet to log visit and conversion events on the page.

Why Performance Edge is faster

Performance Edge takes advantage of the structure of modern content delivery networks (CDNs) to deliver experiments to your visitors faster.

A CDN is a network of servers that are distributed across the globe. When a visitor lands on a webpage, the content on that page is delivered through a server that processes requests, delivers files, and handles content like HTML pages, images, and JavaScript files, over a network connection. Today, most internet content is served through CDNs, including major, performance-driven sites like Facebook, Netflix, and Amazon.

Content that's delivered from a server located close to a website visitor is faster than content delivered from one farther away. A CDN speeds up visitors' experiences of a webpage by placing servers all over the world, often near metropolitan centers.


Optimizely delivers experiments via a CDN. The traffic is routed through servers that are geographically close to your visitor.

Performance Edge leverages an ability to run JavaScript at the edge of the CDN to deliver experiments faster. It runs Optimizely using a "microsnippet" instead of the full Web snippet.

The microsnippet

Performance Edge uses a "microsnippet" that includes only required code. Instead of containing all of the content needed for a full Optimizely project like the standard Web snippet, the Edge microsnippet contains only the JavaScript needed to execute changes on the current webpage for the specific variation that an individual visitor is bucketed into. The contents of the microsnippet are unique to the visitor and webpage.


Performance Edge is a fast, smart delivery method because microsnippet is lightweight. It contains only the content needed to deliver experiments to a specific visitor on a specific page.

The heavy lifting of experiment computation is moved out of your visitor's browser and into distributed machines all over the world, reducing page load time and making it possible to deliver fast, smart experiments to your site visitors no matter where they are.