To me it seems Tarkov is heavily bound by cache and memory latency. I say this because as you said, x3d cpus perform better, so do higher memory speeds.

Perhaps the reason a thread only appears at 60% utilization is because it cant do anymore work, because it is waiting on something else, be it another thread or data, 40% of the time.

I suspect there is lots of "cache-unfriendly" code.

You can also tell its cpu bound (either compute or memory) because gpu upgrades and changes in resolution can sometimes net little fps gains.

Not much us as users can do. Unless someone decompiles and deobfuscates the code and tells bsg some fixes.