As you're Photoshop is not performing as expected, could you please let us know which version of Photoshop are you using and also on which operating system?
I use Photoshop CC 2018 and Windows 10 Pro 64 bit.
I think the problem is that you are reading files directly from the SD-card. And the speed of reading and the response of the device take this time.
Try to open your failes from SSD or NVMe SSD and compare.
I have similar configuration and it work perfect!