OMG, this is the best change ever! I used to have terrible mouse lag when playing the game while duplicating the screen (for gaming nights with my brother where we watch each other play on the TV). With the new rendering this is now gone and the gameplay is much smoother when mirroring the game on my TV. So kudos for the great job. I will continue to play on the PTR and share my feedback.
Edit: Win 10, Ryzen 7 2700X, ATI Radeon R9 290