Introduced in ToolKit v1.3.11, Booster > Headstart gives ToolKit users the ability to easily preconnect and prefetch external resources.
By “Prefetching” an external domain, browsers can begin connecting and downloading a resource faster. This helps improve load and render times and addresses the Lighthouse recommendation “Preconnect to Required Origins“
To use Headstart:
1) Perform a GTMetrix scan or Lighthouse performance audit.
In GTMetrix, inspect the Waterfall tab, identify any scripts that being downloaded/served from an external domain (aka any domain that is not yours). Copy/paste those domains into Headstart > Prefetch DNS
If using Lighthouse or web.dev instead, there will be an area “Preconnect to Required Origins”. Copy those domains into Headstart > Prefetch DNS
2) Click save and clear all levels of cache.