With both Baritone and bobby installed, if you have a world named bobby-fallback in your saves, the game lags heavily in Multiplayer.

Tested this without any mods except Baritone and Bobby and the same issue occurs, as soon as you get rid of Baritone it's patched, not sure if this is a Baritone or Bobby issue.

Probably a Baritone thing. Bobby doesn't really treat the bobby-fallback any different than the per-server cache.