But... the Power of the GPU...
A big thanks to Other World Computing for loaning the 8-core 3.3 GHz Mac Pro and authorized Apple dealer B&H Photo for loaning the 6-core 3.5 GHz Mac Pro.
PhaseOne CaptureOne Pro offers “hardware acceleration”, meaning the GPU(s).
See also Two GPUs to Rule Them All, and in the Software Bind Them—Photoshop CC Now Sharpens 4X Faster.