I have recently tested 2 eGPUs on my Mac Mini 2018 i7, 32GB on Catalina 10.15.7. - RX 560 (4GB) and RX 5700, (8GB).
While I understand that RX 560 might not have a big advantage, there should be advantage for RX 5700. And it is so when using RX 5700 with Windows 10.
Testing the same 172MB .TIF file in Sharpen 2.1.8. (Stabilize, 50, 50, 0.) resulted in:
Time it takes to process the file in W10:
Medium eGPU memory - 3.48;
High eGPU memory - 3.21;
CPU - 4.01 minutes.
Same settings on the Mac:
MAC - CPU - 4.00;
MAC - eGPU - 10+ minutes
… What kind of issue is there with the Sharpen macOS version?