Memory bandwidth is the bottleneck these days.
Bring on the triple channel! I was very upset when I learned that DDR3 implementations weren't supporting triple channel! I think it was only one or two intel boards that would. Of course you could always build a system using server hardware.
I was far more disappointed when I read several articles about how "we don't need triple channel memory". Well ya no shit we can't make good use of triple channel if it isn't available to develop on numb-nuts!
Triple channel is nonsense. It never showed up as beneficial to memory bandwidth outside synthetic benchmarks and very specialized uses. In any case, on the CPU side my personal feeling is that memory bandwidth isn't nearly as big a problem as latency, when it comes to games. It's chaotic accesses and cache misses that kill us. The GPU, on the other hand, can never have too much bandwidth. We're seeing some great new tech on that front with HBM(2) and GDDR5X.
Isn't 33ms still more responsive than 66ms?
You also need to be aware that D3D/GL like to buffer an entire frame's worth of rendering commands, and only actually send them to the GPU at the end of the frame, which means the GPU is always 1 or more frames behind the CPU's timeline.
Of course, VR was where that really screwed us, much more so than input latency. That's why we wound up with this: https://developer.oculus.com/documentation/mobilesdk/latest/concepts/mobile-timewarp-overview/