Thank you - interesting!Here's an interesting test that corroborates what some people in this thread already said:
https://www.pugetsystems.com/labs/articles/Photoshop-CC-2018-NVIDIA-GeForce-vs-AMD-Radeon-Vega-1197/
(UHD 630 is the Coffee Lake version of HD 630, which is used in comparisons)
BTW, the mentioned HD 630 512MB, but surely macOS can allocate more than that? (1.5GB max?)