= 19th Aug 2022 =

Using:
 * Macbook Air M2 (2022)
 * Apple USB-C Digital AV Multiport Adapter
 * Lexar USB 3.0 SD/CF card reader (USB-A)
 * Blackmagic Disk Speed Test v3.4.2

Writing to root of each card, 5gb test file.

||                                                   || Write        || Read         ||
|| (SD) Sandisk Extreme 64gb  90MB/s, V30, UHS-1     || 52.8  MB/sec ||  90.4 MB/sec ||
|| (CF) Sandisk Extreme 32gb 120MB/s, Movie20, UDMA7 || 60-64 MB/sec || 108.3 MB/sec ||

This pages suggests the limits of the D800's write speeds: https://www.cameramemoryspeed.com/nikon-d800/fastest-memory-sd-cf-card-tests/
 * 40 MB/s for SD
 * 70 MB/s for CF

This means the SD card is performing roughly as expected, and can outpace the camera. It fully delivers on its read-speed claims, which is great for getting photos from the card to the computer.

The CF card is a bit on the slow side. If you're writing in Backup mode it'll still be running faster than its SD sibling, but it could do better in the camera itself. It definitely reads faster than the SD card, but not as fast as it says it should be able to.

In both cases, faster cards won't help much in the camera, and for fast-paced shooting the D800 is the wrong tool as you'll fill its internal buffer quite quickly. One of those fancy UHS-2 SD cards would do the job though. As long as the card reader can keep up, you might move files to the computer at about 250 MB/sec.