Low framerate in certain games only in certain regions Bootcamp
The issue I am getting is that when playing games like bf4 or apex the framerate will be 80 except for very specific areas where it can drop as low as 30 , eg in apex when looking at wooden huts (not other building types only these). It's insanely frustrating because these appear independent of resolution or settings and the entire time my egpu utilisation is sitting at 30% and my cpu usage is only at about 50% (not even full usage on all cores).
I should note that my cpu is capable of sustaining boost clocks as it has been repasted so the cpu is not throttling in these regions.
If this is an issue with the cpu being a bottleneck then is there any way to disable the firmware lock on undervolting/overclocking on the macbook's to see if this improves performance.
It sounds more likely to be driver issues to me, but everything is possible.
Towards bottlenecking I was having similar problems with my eGPU recently even on games like Overwatch running on low. The only thing i remember to have changed was updating to Windows 10 1809 from 1803 - which i still hold as the culprit here (but i'm too lazy to finally downgrade it).
However, to answer your question on disabling Turbo boost, you can do so in Windows by limiting the CPU maximum performance to 99% in your Windows energy profile. To do so, go to System Control Panel>Energysomethingsomething>click on change energy plan>advanced settings (a small window should open) search for Processor settings and change maximum to said 99%; this will keep the processor at an almost (if not full) full non-boost clock setting but will refuse it to go into turbo boost.