The CPU cycles billions of times a second, WoW will make use of multiple cores. The draw calls must be received by a single thread and cannot be farmed out to multiple cores.
Go look up processor affinity, how multi-core scheduling works at the OS level, and read up on how the task manager displays the information. Now, let’s go back to this statement and I want you to actually answer my freaking question:
If a person has a GTX 1060 and an i5-8400, they’re playing at 1080p and they want to increase their FPS in WoW; should they upgrade their GPU or CPU? They’re sitting at 35 FPS in Boralus, what should they upgrade to increase FPS? Answer it.