Changing Settings in game.

I'm having issues changing settings mid game.
Say for example I want to change when/how icons are displayed in a game, I'll go to the settings and change the correct option. When I then save and close the settings, I get a black screen for a few minutes and the game then resumes, but remains increasingly laggy.
Also most of the time, the changed setting doesn't even take effect.

I'm using Win7, but a friend on Mac confirms the same.

Known bug - it even says so in the launcher.

Thanks. Sorry for dupe post then, I don't see the launcher as I play through steam.