Ok here is my theory. I had a discussion with one of my friends on our Discord about what could be causing this, and it is simply repeatable. The Advanced displays in the 787 are not optimized and using main thread to render all the graphics for the displays, The software is not using any other threads or GPU to render the displays.
My set up:
AORUS GA-Z270X-Gaming K7 | Intel i7-7700K 4.2 MSI AMD RX Vega 56 8 GB HMB2 500 GB WD Black NVMe PCIe SSD M.2 X4 1 TB WD Black SSD 64 GB PC3200 DDR4
Samsung 32" Odyssey G7 Curved
Default High end settings running 2k with HDR on
First pic shows Out side over LAX. My GpU fans are screaming 4500RPM and full UTIL. 94% is on the GPU. Shows GPU limited,
This next pic is inside cockpit and you can see GPU UTIL is freaking 9% and I am getting 17fps
My GPU Fan is starting to slow it shows 3100 RPM,
I mean 31-35FPS over LAX in high end settings running 2k with HDR on is Real good. ■■■■ good for my system. And I can get that all day with any of the other planes, steam or glass. inside and outside. Now I hear the CJ has the same issues. It comes down to Optimizing the advanced display rendering to not just use the Main thread CPU0