I tested a suite of non-scientific benchmarks to compare performance between macOS High Sierra and Windows 10 (installed via Boot Camp Assistant with the latest Apple-supplied drivers). My primary iMac Pro usage is video editing using Adobe Premiere, After Effects and Media Encoder. Test notes: Premiere Pro test: Render a previous project to DNxHR UHD HQ. After Effects test: EQUILOUD template to lossless. AME test: iStock 4K ProRes clip to DNxHR UHD HQ transcode job. Adobe app launch tests: Time it takes from clicking the icon to being able to use the software. SunSpider: lower results = better JetStream: higher results = better Kraken: lower results = better Octane: higher results = better Here are the results (imgur). Highlighted cells under the "difference" column show tests where Windows won. In general, Windows 10 is noticeably better when it comes to OpenCL and OpenGL tasks. macOS edges Windows in some CPU-bound tests, but not by much. For my usage, I'll rely on Windows. Fortunately, the iMac Pro will be shared by others, so they can choose whatever OS they want for their tasks. The 1TB SSD was evenly split and should be enough.