I have not yet tested for Games yet. B650 has a special GAME Mode which disables all processing (like 100 HZ, DNIE etc. ) which makes picture appear in Sync.
But yes as i have also read read in many forums, there is a little (very little) lag which a hardcore gamer might not like. Some people have also claimed that this can be fixed by tweaking with the service menu for firmware 2004.
Also i believe as samsung also cares about gamers (as there is a provision for GAME MODE Menu) , they will surely update or fix it with new firmware release...
Because i have already found many things fixed within 6 months with 3 firmware updates ..