I have several Sandisk SD cards all rated Class 10. One card transfer files to my computer faster than the others. Specifically I had taken several pictures and used a different card each day.
One 16G card transferred 528 pictures (10.4G) to my computer in 7 minutes. Other cards took hours. For example, another card transferred 508 pictures (9.8G) in 2-1/2 hours. The other cards I had (both 16G and 32G) also took over 2 hours to transfer about the same amount of data.
What is causing this behaviour?