This script should be placed in the head of the page as close to the top as possible. The synchronous container can replace the asynchronous container script, and is able to load both synchronous and asynchronous elements.
Configuring the Synchronous Container
When creating a synchronous container it is important to set a proper expiration window for the container script. The window sets how long the container will last in the users cache and while cached the user will not need to make any calls to the server. However, while cached any updates to the synchronous tags within the container will not be fetched.
Depending on the frequency of updates you may want to shorten or lengthen this window to ensure good performance while still being able to quickly update synchronous tags*. The current maximum expiration window is set to one day, which means users visiting the page after an update will not see any changes to the tags until a full 24 hours after their previous visit.
*Note for testing purposes you can clear your browser cache to fetch updates to the container without having to wait for the expiration window.