Workaround: Input Lag with Nintendo Pro Controller playing Steam games on Mac

I was having a problem where, when playing the game Phoenotopia Awakening on my MacBook using a Nintendo Switch Pro Controller connected to the Mac via Bluetooth, I was getting pretty significant "input lag": About half a second would elapse between me pressing a button on the controller, and the character reacting on the screen, making the game nigh-unplayable.

Oddly, this issue would only occur with my MacBook "docked" -- connected on my desk to my multiple monitors, wired ethernet, and various other peripherals. When using the MacBook as a standalone laptop, the game and controller would play just fine.

Even in the "docked" configuration, however, outside of Steam, an in-browser gamepad tester showed that the controller was communicating with the MacBook with no lag.

I found the following to be an effective workaround for the problem:

1. In Steam (not in "Big Picture" mode, and with the game not running), locate the game in your Library.
2. Right-click the game and select Properties.
3. On the Controller tab, select "Disable Steam Input".

 Voila -- No more input lag with the Nintendo Switch Pro Controller, even when docked! 

 Hat tip to "Toms33" for posting this solution in a thread on the Steam Community forums.