I've been a LR user for years mainly with a 2012 Mac mini quad core. Upgraded this week to the new base 27" iMac (8GB RAM, 3.0 i5 six core, Radeon Pro 570X 4 GB). Ordering more RAM soon. My camera is Nikon D7500 shooting RAW. I'm still putting it though the paces. While this iMac is fast and the display way better than the Dell I was using, I wouldn't say it is way faster than my older mini which also had an SSD. The Blackmagic tests I did do say it is WAY faster though. I'm having one significant issue and was wondering if anyone had feedback or advice. I was hoping to cull my images (NEF) in full screen mode (clicking "x" to delete ones I don't want) When I press "f" for full screen mode in either Library or Develop mode, it takes at least 5 or 6 seconds to switch to full screen and then about 15 seconds to go between photos using arrow keys. Frustratingly slow! Thanks in advance.