I found that on MacBook pro 2018(6-cores), scrool through images is a lot slower than a mac pro 2013(with 2560 x1600 monitor),
not sure if it is because of the screen resolution, but on MacBook pro I already set to fastest preview.
I use the same pm 6 setting on both mac.
when pressing the arrow key faster(or long-press the keyboard arrow, key repeat speed already set to fastest ), the speed of switching photos is still slow,
no matter how fast I press the arrow, it will look like there is a speed limited on it.
when selecting photo actually feel very laggy
but on a mac pro, the speed of switching photos is as fast as I press the arrow.
please check the video, will be deleted after kirk sees the problem, because of clients' privacy
the first half of the video is on RMBP, the 2nd half is Mac pro
http://bit.ly/2Bfz08S