Frontend & browser·The network from the browser
the page got half a second slower and nobody on the team changed any code that week.
Third-party script
Also called3P script, tag
A script loaded from another origin and controlled by someone else: analytics, tag managers, chat widgets, ads. It runs with full access to your page, competes for the main thread and the network, and can change without warning or review. It is very often the largest single item in a performance investigation, and the one nobody has the authority to remove.