this is kinda a little strange situation here, but I was using your miner from the version 1.4.3
it's been working great, then I had upgraded to 1.4.6 and had some problem with pool getting messages of low diff share.. i returned to 1.4.3 - seems working good. now I decided to try your latest version and downloaded it. first I decide to try it on one rx580 card only.. but with the same settings the speed of 1.5.1 is slower then 1.4.3.. it is 970 h/s vs 1010 h/s  ( clocks are 1225 core / 1950 mem)
strange.. I was hoping for some performance boost..