My R9 280x with driver AMD 14.6(11,57Mh/s) do less than 13.12(14,5Mh/s)

Setting:
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
sgminer.exe -k groestlcoin -o stratum+tcp://cryptohunger.com:3333 -u USER -p PASS -I 22 -g 1 --thread-concurrency 11200 --gpu-engine 1080 --gpu-memclock 1000 --lookup-gap 0 -w 256 --auto-fan --temp-cutoff 95 --temp-overheat 85 --temp-target 72

win 8.1
thank Lepra & all