Reducing input lag to a minimum

[kamild1996]

Hello,
which settings are the best for rhythm games in terms of input lag? I've got these options covered:

• "Force real clock sync" enabled
  
• Mode set to "skip buffer effects"
  
• No postprocessing shaders
  
• No V-sync
  

What else should I change? Switching these options above helped a bit but... it's still not quite there It's kind of enough for Patapon but in DJMax Portable 3 the lag is still significant.
The amount of calculation power that can be "sacrificed" in order to reduce the input lag is quite big (Core i5-3350P, Radeon R9 280X).