Hello,
I have Ubuntu 13.10 64 bits, and vertminer 0.5.4pre... downloaded from https://github.com/Bufius/vertminer-gpu‎...
Mobo SABERTOOTH 990FX R2.0 , processor am3+, ram 16Go ddr3....
I have 4x7970 saphire radeon, and they pull 2500 kh/s with cgminer --scrypt (DOGE, Litecoin...)

Now with vertminer, I have 100% HW beyond I 12...
I can only pull 750 kh/s, that's 190kh/s per 7970, it is ridiculous....

My best setting is : ./vertminer --nscrypt -o stratum -u username -p pwd -I 12 --thread-concurrency 4096 --shaders 2048 -w 256

May I have to test the cgminer modified mod https://github.com/Bufius/cgminer, is it better?