EVERY video is slow. Dunno what to tell you. Maybe it's because I'm on the arse end of the world, but it's always a crapshoot whether or not a peertube video will actually load for me or not. Even this one buffered for ~30 seconds before it started playing, which is just too long for it to be a viable yt replacement just yet. I'm getting > 100 mbps down on this machine, so it's not my connection
ETA: I will say, after writing this, I tried a few others, and it does seem to be better than the last time I tried it, so maybe this was hasty. They do still buffer much more than yt, but they seem to play consistently now at least
proceeds to sit directly on the laptop keyboard