Currently, the fastest memory card for new released Nikon D5 and Nikon D500 is the Lexar Professional 2933x XQD 2.0 memory cards (Amazon | B&H Photo Video | Adorama). Lexar USA has posted video reviews for testing Lexar 2933x XQD card on Nikon D5 and Nikon D500, you can see the video reviews below:
Lexar Professional 2933x XQD 2.0 Speed Test – Nikon D5
Lexar Professional 2933x XQD 2.0 Speed Test – Nikon D500