I recently setup a new CF card with PFS3 and cwb 28 on it. Perhaps I stuffed up somewhere because without making any hardware changes, I swapped back to my previous CF card with cwb v27 on it and now my FASTmemory stats are comparable to yours.
My drive statistics however remain unchanged. (today, on both cards they have been about 4x better than on the module I sent, but that is still way short of yours.)
Perhaps 2 different issues?