A:Answer For a comprehensive review and testing on the Sony KD43X720E 43", please see this Rtings.com page -
http://www.rtings.com/tv/reviews/sony/x720e
Quoted from the page's "Input Lag" section:
... Input Lag -
4k @ 60Hz : 19.8 ms
1080p @ 60Hz: 19.7 ms
4k @ 60Hz + HDR: 19.7 ms
1080p @ 60Hz + HDR: 19.7 ms
4k @ 60Hz Outside Game Mode: 120.8 ms
1080p @ 60Hz Outside Game Mode: 121.0 ms
4k @ 60Hz @ 4:4:4: 18.7 ms
1080p @ 60Hz @ 4:4:4: 18.7 ms
4k @ 60Hz @ 4:4:4 + 8 bit HDR: N/A
1080p @ 60Hz @ 4:4:4 + HDR: N/A
4k With Interpolation: 120.8 ms
1080p With Interpolation: 120.7 ms
1080p @ 120 Hz: N/A
Excellent low input lag, which will please all but the most competitive gamers. Both the Game and Graphics 'Scene Select' modes always have low input lag and show 4:4:4 color properly, but never show HDR content properly. The 'HDR' 'Scene Select' surprisingly has low input lag as long as 'Motionflow' is turned off, but it does not show 4:4:4 color properly. Overall the input lag is significantly lower than almost all Sony TVs, and roughly equal to Samsung TVs, but a little higher than most TCL and LG TVs.
Update 10/18/2017: There is currently a bug on the Sony X720E that causes the the input lag to rise after the TV is restarted. To make use of the low input lag, it is necessary to change picture mode to something other than "Game" or "Graphics" then back to either for them to function properly.
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