The hashrate "drops" due to the different effective algorithms in the algorithm-order of X16r. It's not a bug, it's a feature 
I know it's a feature in x16r algo to prevent Asic miners to join mining with gpu miners but i got confused by what member named "S780" mentioned in previous posts. He's claiming to get stable 38 hashrate on Linux OS.This got me confused since my hashrate goes from 20~31