Lightroom Classic: Poor Performance on Mac with 5K display

Do you have the graphics processor unit enabled in Lightroom preferences? Has that made any difference whatsoever?

Yup, I’ve tried it with graphics processor on and off, makes no difference.

You posted a long story without once saying what exactly is the problem...

Forgive me, I wrote this out right after getting off a chat with adobe support and explaining it all in detail to them.

In short, the application slows to a crawl whenever I use adjustment brushes, spot removal, crop, graduated filter...basically any of the basic develop tools.

The answer here may be that you don't have good Mac IT support. I was an Apple Certified Mac IT guy for 25 years, and Lightroom runs just fine on my 2019 27" iMac (3.6 GHz Intel Core i9, 64GB RAM). Question: did you get 64GB of RAM? THIS is the crucial detail in getting resource hogs like Lightroom (which needs a lot of resources) to run properly, and also run Photoshop, a browser, email, etc, at the same time. If not, go to Macsales and upgrade your RAM! Also, if you only have 16GB you could try what I was doing when I had 16GB, running Memory Clean every 5 damn minutes!

But I digress. If you have just "upgraded" your Mac OS several times, and not done a "clean install", you may have tons of "cruft" (technical term) that is slowing down EVERYTHING, not just Lightroom. Doing a clean install of Mojave and then using Migration Assistant to bring your data and apps back from an external boot drive backup may be just the ticket.

Or, if you're lucky, you might just have corrupt caches or application states, or directory damage. Please give your Mac the "once over"! Run the free Onyx (https://www.titanium-software.fr/en/o...), reboot. (In Onyx just run almost everything in the Maintenance tab, deselecting things you may not want deleted, like Launch Services. (Hit the "Options" button and deselect more stuff like Cookies & Other Site Data, Browser History, Form Values, etc.), then hit Run Tasks. After it's done it will ask for a reboot.

If that doesn’t fix it run Disk Warrior if you can ($120), (https://www.alsoft.com), to fix directory damage, reboot. If you can’t do Disk Warrior, at least run First Aid from Disk Utility. Also just doing a "Safe Boot" can clear out caches (restart, hold down shift until you see "Safe Boot" on the screen, then reboot normally. 

If that doesn’t work try launching Lightroom from your other (admin or test) account, with a new catalog, as a test. Does it run OK? If it does it may be a corrupted preference in your Username/Library folder. Check The Lightroom Queen site for instructions on how to reset your preferences (https://www.lightroomqueen.com). Let me know if this improves it?

i am in a similar boat.. very poor performance. and i appreciate other folks offering advice, but a bit of research will show that SOME users experience horrible performance, even on fancy machines.

So what is horrible? maybe one person's horrible is another person's slow is another persons ok.

How about this..i am in develop mode. i got to a never-before editd photo. i hit the crop icon and i grab one of the grab segments on the edge. i click the mouse and drag the edge and let go of the mouse. nothing fancy

Frequently, i have to wait up to 3, sometimes 5 seconds, before LR recognizes that the mouse button was released. if i move the mouse too soon after releasing the button, LR thinks the mouse movements are part of the crop action and i wind up with crop sections that are just a single point.

i can tell that LR registered the button release by some cursor change (cant rememer of the top of my head.

This weird action is only with LR. Not PS. Not vegas. Not On1. Not word. Not outlook. Not chrome.
Windows 10, 32G RAM. GPU disabled/enabled does not matter.

And if you look further, adobe actually suggested (and it worked in my case), to change the core (CPU core) affinity settings for LR - in otherwords, dont let it run on all 8 cores i have, but only let it run on two. That did actually help. a couple of releases ago. Then an upgrade later its back to bad behavior.  But this type of solution shows these type of issues go way way way beyond driver updates or gpu acceleration or cache cleaning.

So i get it sounds like generic whining about slow performance and with that i see lots of generic , but a bit of research will show that LR has, for some users,  really bad performance, and requires some more substantial answers.

Same here. I have iMac Pro. When it comes to processor (importing, exportin, etc..) I see improvement, but overall experience is not what I would expect. Some things are no different from my super old laptop.

Please go back and re-read my post. Unless it’s happening on all machines it’s not a bug in Lightroom (and it’s not happening on my new 27 inch iMac).

Please give your Mac that once over that I suggested in my previous post, because the most likely culprit is damage/waste in your operating system. This is likely to fix your issues, but don’t complain until you’ve done it !

It's not a solution (that's Adobe's job), but a workaround. If you open the LR applications "Get Info" window and check "Open in Low Resolution", LR will significantly speed up. 
Obviously, there is no point in buying a 5K machine and then not run it at the highest resolution, but I rather have a fast UI than the highest possible resolution. As I said, it's only a quick fix. Adobe, over to you. 

Huge slow down when I use my 5K monitor, 75% more pixels have to be processed. Windows and not MacOS but pixel processing is essentially identical for both OS. I had both 5K and 4K monitors on my system and Lightroom is much faster on the 4K monitor; full screen, single monitor mode. Because of driver issues from Nvidia for the 5K monitor, I replaced it with a 2nd 4K monitor. The 5K monitor from HP was beautiful but unusable for 1-2 months out of the year because of Nvidia. 
  

I'm running Lightroom CC 3.2 on an iMac 5k 2019, 3.6GHz 8-core i9, Radeon 580X 8 GB, and 64 GB RAM.  I had an issue with the photo grid flashing on/off, which appeared as a black flash because the background color was black. I found that this flashing only occurred when syncing lots of images. I had just signed in. This happened on two different user accounts. While syncing/flashing, the GPU settings had no effect. Once syncing had finished, the flashing went away. 

An update, for anyone who comes across this. 

Adobe have consistently failed to provide a solution to the issues I'm still experiencing. I have escalated and escalated, had endless chats, calls and screen shares. I've tried all the steps they suggested. Nothing fixes the problems I'm encountering and Lightroom remains practically unusable. It is broken and I've given up trying to get any support from Adobe. 

With the current situation and my city in lockdown, I've finally found the time to properly learn Capture One and I only wish I'd done so sooner. It just works and is a far more powerful, efficient piece of software. And, unlike Adobe, they actually listen to their customers and implement requested changes. Sure, sometimes they take a while to do so, and there are some features/functions missing from the software, but overall it's a significantly better option for me and I would imagine for most others.

I'm looking forward to the day when I can ditch Adobe software altogether. Thankfully that day doesn't look too far off. 

Good luck to those experiencing similar issues - I know all too well how frustrating they are.

Stay well!

Yes Adobe software tends to require powerful hardware and works even better with a modern operating system. MacOS is a modern GUI layered on top of a 51 year old OS, UNIX, which was designed to be highly efficient for single functions. UNIX is not a preemptive interrupt driven OS like zOS or to a lesser extent Windows. When a task grabs the CPU, it owns it until the task is complete. 
 
For Lightroom Export, Lightroom will dispatch tasks for each one of the images to be exported. So for 100 files on a 10 thread CPU. it will dispatch 100 tasks that the OS will serialize; it will almost 100% control all 10 threads until the files are exported. 
 
Assuming that you: 1) don't want to switch to Windows (which is impacted by Export though not as severely) AND 2) want to continue with Lightroom; export to a slow device such as a USB stick and when done, copy the exported files to the desired location. Then the process becomes write gated and there will be CPU resources available for other tasks. 
 
What Adobe needs to do is offer a setting to restrict the number of threads used by export. Many rendering applications offer this feature.   

What we all need is a desktop OS which is interrupt driven with symmetric multitasking. Lightroom is not the only tool with this problem, various non-Adobe video rendering applications have the same issue.  

Hi I'm looking to pick up my first imac a 2017 5k and with 32gb ram and also nvm disk instead of SSD.
I'm also a user of both PS and LR.
So I'm wondering is this only on the 5k screens this issues appears? If I'll go with a 2k screen instead will that help me out. 5k isn't a must for me.
And or is the problem fixed yet?

I have a 5K iMac (2019) and there are ZERO issues with speed with LR Classic. 5K (or 4K) of detail is really good for photo editing. The problem was never the screen resolution itself, it was either the GPU incompatibility, or trying to edit photos with too little RAM memory.