I had not much time for testing due to urgent DCR fix, just noticed slowdown for Polaris on Linux. It is because OpenCL reports that it has 14 compute units (CUs) instead of 36. You can fix it by using undocumented option: specify "-eqlim 288". 288 = CUs * 8. I hate this magic, so I'm working on next update that will have good hashrates with 100% stable mining speed on both Windows and Linux. Just wait a few days.