Tera Raids could be better, Our experiences might be a bit different because in my experience most of my online raids were generally smooth, as smooth as it could be. To be fair, there were like one or two standouts where it didn't function well (e.g.: a long delay before the actual Tera Raid started) so I can't claim perfection.
Still, there are some things that Tera Raids did that makes thing faster that I appreciated. Like how ability or stat activations don't focus on other players one-by-one (except mainly in the beginning with things like Intimidate activating). So like if my teammate has stat drops/boosts individually, my actions don't freeze to wait for those animations to fully play out.
In any case, it happens faster on average compared to Max Raids and it's something I appreciate. 3-star ones are notably faster because you can bring in a powerful Pokemon to just KO and get them over with in less than a minute. Only thing is the inability to switch off animations (something you can do in SwSh, making solo raids faster, unlike online raids which still keep those animations).
Thank you for reading.