I ran a 30 sec burst test using my Nikon D4, 3 times each for my 32G Sony XQD Series H, 32GB Sony XQD Series S, 32GB Sandisk Extreme Pro, and 32GB Lexar Pro 1000X memory cards. I ran the burst test because it gives me a measure of what I can do when photographing flying birds, something I do weekly. It would hold for other moving objects too.
The D4 was set to continuous high speed mode with a fixed focus point. The battery was fully charged.
I pressed the shutter release down for 30 seconds and counted the number of photos I got, shooting RAW, Lossless Compressed, 14 Bit, in manual mode at 1/640 second at an all black background. Here's what I got.
32GB Sony XQD Series H - 157 shots in 30 seconds, 76 shots before it slows down.
32GB Sony XQD Series S - 162 shots in 30 seconds, 81 shots before it slows down
32GB Sandisk Extreme Pro CF - 145 shots in 30 seconds, 70 shots before it slows down.
32GB Lexar Pro 1000X CF - 150 shots in 30 seconds, 71 shots before it slows down.
The results were a little surprising to me, but clearly, as we've seen with other cameras using the latest and the greatest "faster" memory cards, the camera's processor and cache size eventually are the limiting factor. We appear to be at the limit of the processor and cache for the D4 with the Sony XQD Series S memory card.
While the Sony XQD cards are faster reading and writing in the computer, so you can upload your images more quickly with this card, in the D4 we seem to have essentially reached the limit on speed.