The SessionStack script will not delay the rendering or impact the interactivity of your page during load time.
The SessionStack script is edge-cached on Cloudflare's CDN and typically takes under 20ms to fetch. This is very important because browsers will only allow a fixed number of outstanding resources requests at any given point in time. The faster this request completes, the faster it frees up slots for other requests in your page.
The script sub contains code which loads the actual sessionstack.js script dynamically, guaranteeing that it's not loaded until the page is fully evaluated, and requests for all static resources in your page, such as CSS and images, have already begun.
Updated about a year ago