dipping to 22 from 30Mh/s isn't normal.
Benchmarks are synthetic figures, variations are normal when running the same test. The stable hash was the same in all the tests and the real mining hash from the current ETH epoch 138 to the UBIQ epoch 6 was also the same.
ETH
UBIQ
Your vga card is what?
why your DCR speed very high?
my card MSI 480 4G hynix ram, miming dual ETH=173Mhs, DCR=867 Mhs
For RX 580's, try increasing the DCR intensity to 32 in Claymore. That card is a Sapphire Nitro+ RX 580 8GB with Hynix memory and Anorak's Bios mod. 1115 MHz core, 2200 MHz memory overclock.