P: Slow UI when using Mac and Custom Display Profile

I would recommend turning the xmp option on @Aditya Agarwal. Even though I am just a hobbyist, but, also been a dev for over 3 decades and I am sceptical and always keep backups 🙂

It's a minor overhead to start with, but, you are not really concerned if a catalog goes down. You will lose out albums, virtual copies and stacks, the rest will all come back on import.

I moved to Capture one today. I know and realize all softwares have bugs and sometimes major ones slip through. ( I have been a developer for years), But as a person whose business relies on Photo editing software (We deliver close to 75000 images to clients every year), I couldn't afford to play beta tester for Adobe anymore. I know downgrading to 9.4 was a good option, but to do that on 12 ongoing projects with over 1500-4000 images in each project, and creating a new catalogues for 9.4 (cause it does not allow downgrading for obvious reasons), losing all edits and culls, redoing stuff is just way to much time and money wasted as a full time business. I lost more man hours than 5 years worth of subscription. 

I sincerely hoped the update would fix issues, but no. I am keeping the subscription of course as Photoshop is indispensable for now. But that is all that remains in my Adobe software catalogue. So sad.....

Apparently, LR V10.1 has at least 14 identified significant bugs and a whole bunch of crash reports. The latest release doesn't fix the bug being discussed here even though it's of fundamental importance to photographers. If I had run my business in a similarly cavalier fashion, I would have lost all my clients and gone bust before you could say Jack Robinson. Staggering incompetence made all the worse by staggering complacency.

Yes I realize that I've been seeing a dithered simulation. But my target for viewing is a 4K QLED (not OLED) TV so I doubt whether the difference matters. 2019 Samsung Q80. 

@bill_3305731 I think you may be missing quite a lot - like the difference between sRGB and RGB as Andrew pointed out. Also, you say, you have for several years had 10-bit monitors. That is no doubt true but what might be in doubt is whether you have been experiencing 10-bit display. A number of very specific conditions have to be fulfilled for that to happen. Many users are blithely unaware that what they are seeing on their '10-bit monitor' is just a dithered 8-bit simulation. You might like to check that out. Sorry to be a bit off-topic

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I have no opinion on the deep-rooted cause of the performance problem as I do not experience it myself.  Just trying to help folks understand the temporary workaround recommended above.

@Victoria_Bampton_Lightroom_Queen

I see exactly the same thing on my MacPro 2013.  Add a few local adjustments, and the whole system freezes. Only recourse is power cycle.  This is a new bug in 10.1, it isn't there in 10.0.  GPU Acceleration off seems to fix it, but I'm done taking risks.  Seriously thinking about being done throwing money at Adobe too.  This is getting beyond a joke.

Note, I'm running many other applications, including several Lr rivals, and other GPU accelerated apps, and seeing no issue whatsoever.  It's only Adobe. Well, actually, it's only LrC.

"Now, LR is having performance trouble with some custom-made profiles."

But there is something else that triggers this. The same custom-made profiles do not make LR10 behave the same on different systems.