Input lag is better than average, and should be fine for most people. When the TV detects a HDR signal it switches to a HDR picture mode, which has fairly high input lag. For the best result with SDR content, change the picture mode to 'Game'. The input lag performance is the same as the E6, and slightly different to the B6. A video of the input lag differences can be seen here.

Update 11/08/2016: Some owners have started a petition to LG to address these issues. This can be found here.

Update 12/02/2016: With the newest firmware update (04.30.19) there has been the addition of a HDR gaming mode. In this mode the HDR input lag is lower, and should be fine for HDR gaming. Note that although the TV accepts a 4k @ 60Hz @ 4:4:4 + HDR signal, it can't accurately display the chroma subsampling in any HDR mode, even with the 'PC' icon selected. The HDR chroma subsampling looks the same as the B6, visible here .

Update 01/24/2017: The input lag has been updated for the newest firmware (04.30.95). The results are almost identical.