Twitter is website that contains "links to" the other 5 websites. Those "links to other sites" are really links to Twitter scripts that do database queries before finally linking to the other sites for real. It is easy for elmo to insert delays in the process.
Net neutrality is about Internet itself. Twitter/X is a service build on top of the Internet, so no.
It is for example when your Internet provider Gomes you 100Mb/s, but only when accessing these particular sites, otherwise it's 1Mb/s.
It has nothing to do with data caps or overall speed limit, as some suggest, or with speed on the other end.
Yes, actually. In Québec, Videotron offered a mobile data plan that included unlimited data exclusively for the Google Music service. The CRTC told them that this was illegal and it broke net neutrality laws.
I think I recall reading now that they had implemented it here. The whole "what happens there, happens here" dynamic made me cancel it out when they cancelled it down there I guess.