After reading this thread, I think the result came from Nagorak makes sense to me. When go wireless and if you need to set your SS high, then you need to sacrifice the performance. That's why I set my SS like 100%.
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I haven't tested out to see if it was fixed, however I think I know why performance was bad before and why reducing SS helped improve performance. I discovered that if my GPU was completing the frame later, even if it was still below 12ms (staying out of reprojection), it would cause late starts on the CPU. Meanwhile if it was completing the frame faster this wouldn't happen.
Basically it seems like the Wireless Adapter inserted an extra step between the GPU completing the frame and the CPU starting the next(?) frame. It appears to work like this:
Wired: GPU completes frame > CPU starts next frame.
Wireless: GPU completes frame > WA Compresses Frame > CPU starts next frame.
So, if your GPU is finishing closer to the 12ms mark (usually what would happen if you are increasing SS to maximize image quality), then the CPU would end up starting late and if it was late enough it wouldn't finish in time resulting in reprojection. Meanwhile if your GPU finishes faster (lower SS), it gives more time to compress the frame before the CPU needs to start the next frame.
Assuming the problem has been fixed, I suspect what has changed is now the CPU is not being held back from starting the next frame while the previous frame is being compressed, and instead they are occurring concurrently.
Source: https://www.reddit.com/r/Vive/comments/9yvf02/new_steamvr_beta_completely_resolve_performance/