Have you tried uninstalling the Creator's Update?
Most of the problem happened without the creator's update. I have just installed it recently to see if performance got better.
Nobody? Thought I could get help from intel support here.
This message was posted on behalf of Intel Corporation
I understand the processor usage goes up to 100% with Battlefield 1. Let me try to help on this matter.
I noticed you are overclocking the processor, this means you have changed processor and memory settings. This might cause this type of issue. Please bear in mind the support for an overclocked processor is limited at Intel, no matter if the processor is unlocked.
Have you tried patching the game?
Additionally, I found this thread:
Hope it helps.
So why does cpu usage drops to 60-70% in windowed mode? It's the same resolution and frame rate.