The only thing I knew about 'tag manager' before this was that it was always blocked by NoScript. Your comment made me go look up what it does and now I know that I will never unblock it.
Apparently it lets people drop in random code from a bunch of different analytics platforms, so it's pretty much guaranteed to consist entirely of the sort of stuff I have NoScript enabled to block in the first place.
I've seen GTM take down production multiple times because of marketing shipping random JS with no approvals.
Some random guy in his basement assured someone in marketing they could handle our volume? Chuck their tag in and watch their website get DDoS'ed with millions of requests per minute, which takes out our website because marketing made it fail loudly.
I'm surprised that GTM doesn't handle that. They would have a good idea of how long requests are taking to different domains and limit requests to the slower ones.
Apparently it lets people drop in random code from a bunch of different analytics platforms, so it's pretty much guaranteed to consist entirely of the sort of stuff I have NoScript enabled to block in the first place.