Lr Classic. 9.3 CPU Hog during export - Mac

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This conversation has been merged. Please reference the main conversation: Lightroom Classic: High CPU usage makes it unusable during export

Exporting and publishing from Lightroom Classic 9.3 on my iMac (27" 5k 2017, 64gb RAM, OSX 10.15.5) renders the machine unusable..   CPU%  has gone over 800% !!!  ter is t
he computer inisorkeytokesn.

Right, I'll try again.  When I'm exporting rom LR Classic 9.3, the CPU usage is going through the roof - so much that I can't even type - the keyboard doesn't recognise half of the keystrokes because the system is running so slowly..  it's awful.  It's been getting slow the last couple of versions..  I've just had to install CPU Setter to limit the process in order to be able to edit this post.  

It's averaging 500-600% CPU resources, but has peaked at over 800%... 

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Jason Sheldon

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Posted 1 month ago

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Carlos Cardona

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You could have a corrupt cache, application state, or just directory damage causing your memory leak. Give your iMac the "once over". I was a Mac IT pro for 25 years, and I've done this thousands of times, no problem.

Download the free Onyx (, select the Onyx version for your OS, download, run it, reboot.

In Onyx run almost everything in the Maintenance tab, deselecting things you may not want deleted, like Launch Services . Hit the "Options" button across from Internet and deselect more stuff like Cookies & Other Site Data, Browser History, Form Values, etc. (most of these are OFF by default). If you don’t know what something is, Google it, or don’t run it, or ask me), then hit Run Tasks. After it's done it will ask for a reboot.

Also try to fix any directory damage by running Disk First Aid from Disk Utility: boot into Recovery Mode, (hold down Command-R when booting). When you're in Recovery Mode go to the Utilities menu and launch Disk Utility, say Repair Disk. When done go to Apple Menu for Startup disk and restart normally.

Let me know if it works?

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