Although I try to avoid folding for PPD, that 8018 does discourage me from wanting to keep folding with the price of electricity for GPU folding. Hopefully I will start getting a few more WU with the QRB mixed in.
check you driver. I know before the 32x.xx drivers worked much better for folding.(I don't remember the exact driver right now and I'm away from my folding meachines) I have a GTX 770 and it went from about 30k ish to 81k on an 8900.
While a higher numerical value is rewarding, you can take some solace in the fact that other people are also getting the WUs that have a lower PPD. As long as you are not the only one getting them, then competitively you are still with the pack (and curing diseases to boot!)