When pausing a singleplayer world using esc or f3+esc, mobs, water and lava flow, and damage to the player stops but the worldborder does not. I don't know if this is intentional or not but it is weird.

How to recreate:
1: /worldborder center ~ ~
2: /worldborder set 10
3: /worldborder set 1 20
4: Pause the game.
5: The worldborder keeps advancing as if the world is not paused.