1.6.8 hashrates is lower for me

cards (both sapphire nitro+ 4gb) / hashrate 1.6.7 / hashrate 1.6.8
rx470 / 740 / 720
rx570 / 760 / 740
algo: bittubev2
i switch back to 1.6.7
Going to investigate

same troube on cn-heavy. need to test new upload 1.6.8 or wait new version?
possibly heavy algos impacted. Wait for next version, until then use 1.6.7