Well, there will be insane qeues in Log In menu on Ragna or Cerb anyway (I see short qeue every day). But for me personally game lags much less after split than it was before it. Though I think 5.0 start will be a nightmare anyway.

As for duties - it's pre-exp period when people aren't very active but yeah, waiting time for dungeons became longer. Not critically, but still.