I don't know if this is at all common or not, but it happens to me pretty often...When I play in 3 bar matches (and good 2 bar matches), generally things are totally fine, but when I play 4 bar matches, they seem to alternate between normal and basically playing like a 1 bar match. In fact, I've played 1 bar matches that are better than a lot of the 4 bar matches I've played in, just because they were consistently slow, rather than randomly picking up gigantic input delays.
In any case, it seems to me that a lot of the 4 bar connections I've played are very unstable, and the actual connection quality fluctuates during the match, unlike in 1, 2 and 3 bar matches.