u/eternal_madara

Disabling Windows Fullscreen optimizations for more FPS is giving you double the latency, input lag in League borderless mode. Let me explain:

If you monitor LoL using Intel PresentMon,

This is what you want: Independent Flip: The game bypasses the Windows Desktop Window Manager (DWM) compositor and sends frames straight to your monitor with 0ms added buffering.

But if you get Composed Flip, this is what causes latency. Windows forces game frames through the DWM compositor first, adding 1 to 2 extra frames of buffering.

For +200 FPS, this adds roughly +4-10 ms latency and for sub 140 FPS +14-20 ms latency.