Where it gets unclear is how Apple has the internals connected: the Display and SSD are connected to a PCIe bus, and perhaps one USB port as well, so it is likely that the other lane may be used for the Thunderbolt port and USB ports. However the Macbook Air has only on PCIe 2.0 x2 bus, so it is limited to 2 'channels'.

The Macbook Pros have two Thunderbolt ports, because they support PCIe 2.0 x4 buses, which means they have 4 'channels' of PCIe, somewhat analogous to PCI slots back in the build-your-pc days.

SO I don't think the CFast card or the card reader is at fault - what brand of card reader are you using? I just don't wait for the CFast card to download now, it is lickety split. I am using a pair of Sandisk 500 USB 3.0 SSDs ( 480 Gb ) for my storage in the field. If it is very fast, then that would make me think the Thunderbolt to ethernet connection might be playing a role. My first thought would be to try to download from your CFast card to a single high speed external SSD and see how long that takes. I have been on trips where 10 or 20 Gb of image files would take half an hour or more through USB 2.0, so this is a nice breath of fresh air.ĭo you think the Thunderbolt to ethernet adapter has any effect on downloading speed? USB 3.0 does not seem limiting in my limited experience with CFast cards. I just started using the Sandisk 128 Gb CFast 2.0 card that came with my 1DX MK II - I can download about 64 Gb through a USB 3.0 CFast card reader to a Sandisk USB 3.0 external SSD in just a couple minutes - I was amazed just how fast it flew through - Now, that is not importing via Lightroom etcetera, just a direct drop and drag with finder on my 2016 13 in MacAir.

Mac ethernet adapters duplex issues