P: LrC 12.2.1 fails to start/launch or is extremely slow launching.

So the fact is that there is no workaround, the version with the removal of the "metrics.json" file has no effect on the speed of Lightroom. And Version 12.1, which started the problem, came out back in December 2022, now it's April 2023 and update 12.2.1 came out, which did not fix this bug. Well, let's wait a little longer.

I do think it's a bit premature to think about a whole Software-change (at least it would be for me), but I myself am wondering too why it takes Adobe so long to drop an update on this matter. A lot of users use this software as professionals and lose money on this. How long long will it take until an update comes out?

What makes you conclude that Adobe is not going to solve this problem? The current advice is just a work around. A permanent solution can only be implemented in an update. So perhaps you should not jump to conclusions and at least wait for the next update.

FRIENDS!!!
Everyone who has a problem with slow Lightroom work since version 12.1 + in module DEVELOP, I say at once, have no illusions, removing the file "metrics.json" will not help you, someone may think that Lightroom began to work faster, it's all complete nonsense, just after every reboot it works faster, the problem is much deeper, which ADOBE is not going to solve! The latest stable version of Lightroom is 12.0.1! It works fast and stable, after it ADOBE did something to the program that is not possible to work without nerves, I wrote a lot on the forums, no one wants to solve it. I went back to version 12.0.1 and lightroom works great! The reason for the slowness of later versions is unknown! I noticed that during the lightroom on vindross 11 almost does not use the resources of the system, the processor loaded to the maximum of 20%, the memory is the same. Disabling the video card slows it down even more. 

Why is it not possible to work in the latest versions, at startup? At the beginning the first 20 photos are processed quickly, and then as if someone is holding the program by the reins and shouting STOP! photos are scrolling slowly, you have to wait for 3-5 seconds until you go to the next photo, all the corrections work with a big slowdown, reloading Lightroom helps again until the first 20 photos. The catalog is optimized, the drivers are all new, I'm an experienced user, do not need to tell me about ADOBE tips to speed up, I know it all! Just solve the problem! Why is 12.0.1 stable?

I´ve the same problem here on my win-pc V11 with all WIN updates installed 😞

Hello 

my Lightroom classic won't open, I click on it to open and nothing happens.  Can anyone help, I have my uni work on there and I have no other access. I have an assignment due and need to photos.

thanks Jen 

@mojave_gal, deleting that file can be persnickety -- try the complete steps here:

https://community.adobe.com/t5/lightroom-classic-bugs/p-lrc-12-2-1-fails-to-start-launch-or-is-extre...

Hmmm. I'm running LRC 12.2.1 on Windows 11. There is no metrics.json file in the AppData folder. LRC opens, but really slow, and some activities to seem to lag just a bit.

Thaks everyone!! Removing the metrics.json file has done the trick!

Through all the trails of trying to get lighroom classic to open, I deleted my cloud account, reinstalled, reinstalled lightroom classic, I have to say my lightroom classic is running better then ever! 

I hope it contunues 😃

 Mac: /Users/<username>/Library/Caches/Adobe/Lightroom/metrics.json
(Note that Mac has two Libraries
Make sure you are in the User Library and not the System

@Henry9808,: "No metrics.json file."

Deleting that file can be persnickety -- try the complete steps here:

https://community.adobe.com/t5/lightroom-classic-bugs/p-lrc-12-2-1-fails-to-start-launch-or-is-extremely-slow-launching/idc-p/13695275/page/6#M41952