I do have an almost new iMac (27", i9, 32gb ram, 512gb SSD, middle of the GPU options, 5k display + fullhd second monitor, Catalina, all up to date).
using it to do graphics design (InDesign, Illustrator, Photoshop, Acrobat, all CC2020 versions) and webdesign (code editors, FTP, browsers of all kinds).
after a fresh boot, everything is fine and responsive. opening some code editor, finder, browser, … is good.
doing some work in acrobat, InDesign, illu, photoshop and having some more complex files open, the whole interface (including finder, typing text in the editor, animation or scrolling in browsers, opening save dialogs, …) gets very unresponsive, like low frame rate in macOS animation, spinning wheel when selecting text, and the Adobe apps themselves too are slow on display changes.
I can't see big CPU loads in the activity monitor, but it's hard to see what's going on on the GPU level.
closing the bigger apps again seems to make things a bit better after some minutes, but only a reboot cleans everything up.
currently it's so bad its inhibiting my will to do work – I'd expect that kind of computer to run some mid-level graphics design tasks smoothly … the documents are not simple, but they are nothing exceptional (and my older Mac from around 2015 actually did manage that, but but it was not with Catalina).
As it is a problem even when the Adobe apps are only waiting in the background while I'm in a browser or code editor, it may be connected with macOS itself, not only an in-application performance problem where Adobe would be the clear culprit. Something to do with the graphics subsystem (driver, …?) that is under some stress when using the Adobe applications?
Any idea is welcome …
Best Answer
okay, today I tried to solve this with a hint from the Adobe forums: some people said the performance gets significantly better when using the colour profile "apple RGB" for all attached monitors (instead of using "iMac" or some real colour profile from a calibration tool).
and indeed, that worked, I can now have InDesign or acrobat open and still use a browser or finder or text editor without spinning wheels. this seems to be Catalina+cc2020 only, every other combination seems to work with profiles.
it's no real solution as I need profiling and color management, but at least I've found the cause.
Who is the culprit is hard to tell - apple changing color management methods (64bit? other layer in the display stack?) or Adobe not able to cope with it after now 8 months of CC2020 on Catalina ...
Adobe forums thread: https://community.adobe.com/t5/indesign/inddesign-2020-slow-performance-on-macos-catalina-10-15-1/td-p/10715300?page=1