The whole app has become slow

[alexcoppo]

Problem:

The whole app has become buggy and is lagging heavily in Develop module.

Using the brush 2 weeks ago was completly normal- smooth and responsive however now the cursor and applied effect on the image lags heavily.

Occasionally while applying brush effects the rest of the image will "flash" subtly as if unable to maintain the previously applied changes to the image.

Upright (guided) transform causes the app to freeze for up to 60 seconds while placing reference points.

Troubleshooting that has not worked:

Toggling "Use graphics processor" (no difference whether Off, Auto or Custom)

Optimising catalog

Creating a new catalog

Opening the app in Low Res

Quitting all other apps

System details: 

iMac (Retina 5K, 27-inch, 2019) 

1 TB SSD (40% free space)

Processor: 3,6 GHz 8-Core Intel Core i9

Memory: 72 GB 2667 MHz DDR4

Graphics: Radeon Pro 580X 8 GB

[johnrellis]

What's the exact version of Mac OS (e.g. 11.3.1)?

[GoldingD]

Some general observations

Toggling "Use graphics processor" (no difference whether Off, Auto or Custom)

Auto, Ok, Off, Ok if required, but Custom, usually by users for which Auto results in Basic, forcing things by going to Custom, often bad.

Opening the app in Low Res

How? By scaling? Scaling does not change resolution LrC has to create pixels for.

Troubleshooting that has not worked:
Toggling "Use graphics processor" (no difference whether Off, Auto or Custom)
Optimising catalog
Creating a new catalog
Opening the app in Low Res
Quitting all other apps

At least two items you did not include.

I will leave the second for a followup reply

But first up, did you try cold booting the computer? Turn it off, wait a few, turn it on.

[Earth Oliver]

if you reset the image, then apply only a brush adjustment, does performance change?

[GoldingD]

Second item not included in your troubleshooting

Restore Preference file a.k.a. Resetting the Preference file.

The preference file can get corrupted leading to buggy behavior. A corrupted Preference file will survive updates, upgrades, un-installs, re-installs. 

Restoring/Resetting the Preference file is basically deleating the old file, and letting LrC to create a new one.

Be aware that in doing so, the settings in Preferences, will change to defaults.

see: 

https://helpx.adobe.com/lightroom-classic/help/setting-preferences-lightroom.html

and

https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/

[alexcoppo]

I can't seem to reply to individual replies in the thread so here goes: 

@johnrellis Version: 11.5.2 (20G95) (auto updates are on and I see 11.6 is ready and waiting)

@Earth Oliver sadly not. If anything it slows down even more while it thinks about how to show the image in its original state

@GoldingD  turning computer off and on has been done multiple times to no avail. It sat off over the weekend (I shut it down on Friday, no sleeping)

It might be time to get rid of the preference file and see if that works. 

Thanks for the help- I shall report back!