I've recently purchased a 2016 13-inch MacBook Pro w/ Touch Bar and I've noticed something incredibly strange when playing games. Left-clicking with any pointer (either the trackpad or mouse) results in a noticeable delay in a game's response. So far, I've noticed it while playing League of Legends, Borderlands 2, and Mark of the Ninja.
In the case of League, left clicking doesn't cause the game to freeze up, but rather the game does not register the left click unless the click is held down for a longer time. This is true for both a mouse and the trackpad.
For BL2, left clicking anywhere, either in the menus or in the 3D environment , will result in a slight delay before the click is registered, but will then visually lock up cursor movement. Objects in the 3D environment still move at full FPS, but the player First Person camera will briefly freeze, then cut to where it WOULD be if the freeze never occurred. In this way, left-clicking doesn't freeze the game per say, but rather freezes movement of the game camera briefly.
Mark of the Ninja has an issue similar to League, where left clicking is not registered unless the click is held down.
From these three scenarios, I am led to believe that the issue does not lie exclusively with the trackpad or mouse (since the problem occurs with both input mechanisms). I also believe that the problem exists outside of Steam (which was used to play both BL2 and MotN) since LoL was affected. I have tried adjusting double-click speed in Trackpad and Mouse settings, which did not help. I also tried turning off Force-Click and Three-Finger Drag for the trackpad, which also did not help.
The problem seems only to occur in games; navigating around the Desktop and Finder is speedy and responsive.
Has anyone else had this issue and/or knows how to fix it? I am running MacOS Sierra 10.12.5.