I found out that the 2D tearing/flickering usually happens if the memory clocks are set too low in desktop mode. Running:
will show you the current clocks.Code:aticonfig --adapter=0 --od-getclocks
It might be smart if you Alt+Tab out of your TF2 and run this command. The clocks should be at peak, if they aren't, this might be the cause of lag.
If you wan't to know what else aticonfig can do, you can run: