Hi guys,
Just to be clear again, all I was saying is that you are hitting a CPU bottleneck, and specifically a CPU bottleneck regarding the speed of each individual core. More cores (and especially) hyper threads will not help with this. Because the CPU is the bottleneck the GPU usage will drop, and the GPU usage dropping will be especially apparent on fast GPU configurations like SLI or Titans. And more so at lower resolutions. (At higher resolutions the GPU will have plenty of work to do...)
I'm not sure what you are trying to convince me off. That these spots are specifically CPU heavy, much more so then some other spots? I am not disagreeing with that at all. This is fact. The main contributor to this performance drop is the LOD setting, and you can obviously set this to a lower setting to improve your performance. Also note that both the game and the driver contribute to CPU time spend, so it is quite difficult to compare with so many variables in play.
One thing you can do with the game right now, on the latest patched build, is that you can set the game registry setting Graphics\MultiCoreFlushMode (you will have to add this registry key) to 1. With this set to one it enables new functionality in the game engine that can increase framerate in these spots by up to 50%. You may want to try it out to see how it works for you.
Note that there are reasons this has not yet been enabled by default, testing has been limited, and the well known severe corruption and crash issues on NVIDIA hardware have been seen to occur more frequently and on more machines with this enabled, so please use with caution.