How to identify if graphics settings or CPU cause slowdown?

In strategy and simulation games where slowdowns occur, does tweaking graphics settings noticeably impact the CPU load or smoothness? Have you found specific graphical features like shadows or post-processing to affect CPU-heavy tasks like AI and simulation calculations? I'd be interested if anyone has tested what adjustments actually make a difference in reducing stutters or frame drops when bottlenecks seem tied to CPU workload rather than GPU performance.

Some strategy games rely heavily on CPU for simulations and AI, so graphics tweaks won't always help. I've seen cases where lowering shadows or post-processing barely shifts CPU load, because the bottleneck comes from background computations, not rendering. It really depends on whether the game offloads those tasks to GPU or keeps them CPU-bound. Have you tried systematically disabling certain effects one at a time to spot which might indirectly ease CPU bottlenecks?