Input latency/thread synchronization commit?

[WAZAAAAA]

Where can I find the input latency change documented in this Fortnite patch log?

While working on Battle Royale we identified some issues with input latency in the engine that particularly affected 30Hz games. We were able to make improvements to thread synchronization, reducing latency by around 66ms (the reduction will be around half that in a 60Hz title) to address this problem. These changes make a noticeable improvement to the feel of the game, making it more responsive and easier to aim. (Will be in 4.19)

https://www.unrealengine.com/en-US/b…-battle-royale

Is the code available yet? Does anyone know the exact commit for it?