# Mac slow down after update to Big Sur



## guzzibob (Jan 5, 2021)

After updating my 2019 iMac to Big Sur, computer started to run slower. Lightroom starts out slow and after working for a while gets VERY slow. I'm about ready to go  back to Catalia but don't know how to do this. Can you help with this?


----------



## Paul McFarlane (Jan 6, 2021)

Hi

I assume you mean you're on Classic 10.1. Try two things first:

- in Preferences > Performance, set GPU to off - see if that helps
- if it doesn't, try rolling back to 10.0 (some, including myself, have found 10.0 better for performance)

https://www.lightroomqueen.com/roll-back-update-previous-classic/


----------



## clee01l (Jan 6, 2021)

One other thing,  the current Big Sur version is 11.1.    I am running LrC 10.1 and MacOS 11.1. I'm not seeing problems with either (albeit, I am not taxing Lightroom heavily).   Another thing to try is run the activity Monitor as a background task and if the system starts too slow down, take a look at memory and CPU usage.


----------



## guzzibob (Jan 7, 2021)

Paul McFarlane said:


> Hi
> 
> I assume you mean you're on Classic 10.1. Try two things first:
> 
> ...


Thank you I will try that


----------



## guzzibob (Jan 7, 2021)

clee01l said:


> One other thing,  the current Big Sur version is 11.1.    I am running LrC 10.1 and MacOS 11.1. I'm not seeing problems with either (albeit, I am not taxing Lightroom heavily).   Another thing to try is run the activity Monitor as a background task and if the system starts too slow down, take a look at memory and CPU usage.


I had Apple on the phone for a couple of hours to make sure it wasn't a problem on their side.  The tec person had me delete Big Sur 11.1 and re download it. That seemed to help briefly then it just went back to the slowdown again. Lightroom boots up very slowly then bogs down as I work along to the point of frustration. On start up the Activity monitor shows very high CPU usage  (98 %). 
I do not know how to return to the earlier version of Lightroom.


----------



## Ed Anderson (Jan 7, 2021)

Open the CC app > click the 3 dots > Select Other Versions > It opens another window, select the version you wish to install.  I can see older versions of LrC back to 8.2.1.

Ed


----------

