P: Slow UI when using Mac and Custom Display Profile

Don't matter. all profiles from this applications...

i1Profiler or bassICColor built it? Or maybe both cause issues?

Here Eizo Colornavigator, i1profiler and basiccolor display. Everything the same...

*Tracy Bishop Yes, seems a display profile issue for some, depending on how the profile is built. What could be useful is to report what kind of display and what software created the profile. 

5 year old iMac, Catalina 10.15.7.  Same problems with Lrc10 running slow then completely crashed about three times. Ran Disk Utility First Aid, still no joy. Then found this thread. Changed monitor profile to SRGB.....Bingo! Joy of joys all good, for now. iMac still has it's own issues but at least I can work on my photos again.

I do think that for a £9.98 a month subscription Adobe need to work harder to get these things sorted out. There seems to be an issue every time there's an update.

To downgrade (which I did straight away) Go to the CC application and alongside the Lightroom Classic entry you will see three dots (...) click on this and one of the options is "other versions" Click on that and you will see all the 9.x versions.

Downloading it seemed a very painless solution but what you must do is go back to the catalog that ran with your last 9.4 version. LrC doesn't overwrite the catalog, just copies it. The only thing you will miss is the previews which will remain with the V10 so it will run a little slowly at first as it rebuilds the previews.

lightroom painfully slow after upgrading to version 10. I have after reading here created a new screen profile which is a bit faster but still very slow and instead of lightroom being fun it is now sooo frustrating. I really hope adobe is working on this as this is not acceptable. Unfortunately my catalog is now version 10. can i downgrade it to version 9 so i can go back to the previous version of lightroom and where do i find the older version?  

MacBook Pro 2018

2gb SSD (1gb free)

32 gb RAM

2.9 ghz 6-core i9

Radeon Pro Vega 20 4 GB

Lightroom is practically unusable.

Lightroom Classic performance is now terrible on Version 10
The performance is very bad now and I never had issues before, my performance was really good before this...
The GPU acceleration actually makes it worse,,,
I cannot go to the previous version because the catalog was also upgraded. 
If I restart LRc the performance is mildly better but quicly degrades, 
I cannot work like this sadly.  . . . . 
 
(iMac 2017 , i5, 16G RAM w/ Radeon Pro 580 8 GB)
  Model Name: iMac

  Model Identifier: iMac18,3

  Processor Name: Quad-Core Intel Core i5

  Processor Speed: 3.8 GHz

  Number of Processors: 1

  Total Number of Cores: 4

  L2 Cache (per Core): 256 KB

  L3 Cache: 6 MB

  Memory: 16 GB

  Boot ROM Version: 428.0.0.0.0

  SMC Version (system): 2.41f2

Radeon Pro 580:

  Chipset Model: Radeon Pro 580

  Type: GPU

  Bus: PCIe

  PCIe Lane margin: 0;">  VRAM (Total): 8 GB

  Vendor: AMD (0x1002)

  Device ID: 0x67df

  Revision ID: 0x00c0

  ROM Revision: 113-D000AA-931

  VBIOS Version: 113-D0001A1X-025

  EFI Driver Version: 01.00.931

Same problem. 10.0 is completely unusable. I get a spinning beach-ball with every click for 5-10 seconds, incredibly laggy.

2013 Mac Pro, 6-core, 32GB RAM, FirePro D700, SSD, Mojave 10.14.6

I had to downgrade back to 9.4.