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I also want to add myself as a +1 of another user of this same issue, with the same configuration:
I have the same issue on my 2017 MacBook Pro (onboard Radeon Pro 560 4GB) with eGPU Radeon RX 580 8GB. When Running XP11 I get 20+ fps with the onboard Radeon Pro 560 4GB but only 10 +/- with eGPU Radeon RX 580 8GB
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