I click on a Duplicant to see their status, while time is unpaused, and the game drops to about 15 FPS when I try to move the camera. It even happens if I click on the follow cam option. Any action that causes the camera to move will cause it, actually. I've tested this with several duplicants and oddly enough it happens with all of them except Max, Gossman, and Nails.
Steps to reproduce:
Make sure time is not paused.
Select a duplicant, except Max; Gossman; or Nails, so their status box is open.
Pan the camera or select the follow cam.