From what I've read, the new XQD card is faster than every CF card except the new UDMA 7 compliant Lexar 1000x CF cards. Short of the 1000x card, it seems to make sense to set the XQD card as the first card.
There are two questions that come to mind here. First, what is the speed of you CF card? 300x...600x?
The second obvious question is whether you tried another CF card? Did you try it again in your D700 to make sure it is still working correctly?
I filled the 32 gig XQD card the other day and it moved to a 600x Sandisk CF card. I didn't really notice any slow down at the time, but replaced the full XQD with an empty one soon afterwards.
30 seconds is way too long, so it sounds like you have a faulty CF card or an old, slow one.