That’s inaccurate. You do still need to run a client side GTM script that adds event listeners for specific actions (like “clicks purchase button”). This is the

That’s inaccurate. You do still need to run a client side GTM script that adds event listeners for specific actions (like “clicks purchase button”). This is then sent to a server side container with whatever first party identifier the site may have (3rd party IDs aren’t supported as there’s no 3rd party cookies from Facebook and the like). From there a server to server network request is made to whatever tracking platforms (GA, Google Campaign Manager, etc). Most of the tracking script these days is well written, at least the Google and Facebook libraries, so they generally don’t affect page performance, but some of the smaller players have script that can slow down performance. With server side GTM, only it’s client side component needs to run, everything else will be server side.