Buy an external card reader.
Copy images from card to HDD/SSD before you import them. Does the copying go faster? If not you have a hardware problem.
I tried both: the internal and the external card reader (Lexar USB 3.0 UDMA CF/SD-Reader).
As that didn't make a difference, I wanted to know whether importing from de SDD would improve the speed. Unfortunately not. Moreover, the performance issue started after a software update I did only a few weeks ago.
So I still wonder what causes the performance issue.
Are there videos on the camera card?
No there are no photo files on the cards that I used.
By the way: the GPU is disabled
Do you mean to say there are no videos on the cards you used?