P: With Sync Active, Adaptive Presets are slow to apply and become unresponsive.

What is the amount of albums and collections in your test catalogues? I am beginning to think that might be crucial and that might be why not many users are encountering this bug. It started with "collection album creation slow" right? So I am still observing this same behaviour even with Cloud Sync completely turned off (although to a lesser degree of severity). But HERE"S THE CATCH: I have a gazillion of various publishing, disk publishing and regular collections and albums and smart collections with THOUSANDS of pics. I think the new algorithm might be trying to sift through all of those WITH ZERO NEED (due to faulty code) and the result is that ONLY THOSE USERS who have many collections in their catalogue are experiencing these lags. Try improving your test procedure by including testing for catalogues with lots of collections and albums (whatever you call them, I guess Adobe can't decide on terminology)! 

Bottomline: Bug is still there. The catch might be in number of albums/ collections in the library!

Cheers

I wonder why I am observing the VERY SAME behaviour that was introduced A YEAR AGO with the update to sync engine? When my sync is on (even with no images in queue) the above mentioned operations lag and freeze. When sync is off - I need to completely delete the cloud library fo that (just setting sync on pause does not work) - ALL THE LAGS disappear! 

Please note that I retested your most recent steps on two separate M-series Macs with completely dissimilar catalogs and images. 

Mac 1
1 - Catalog with 400K Images 
2 - 5000 images synced
3 - Takes 1-2 seconds on first - 10th attempt tested
4 - Takes <1 second per image on up to 20 images tested
5 - Takes 1-2 seconds, depending on the number and method
6 - Since I cannot induce a lag, I am not able to verify a quit failure.

Mac 2

1 - Catalog with 50 K Images
2 - All images synced
3 - Takes 1-2 seconds on first - 10th attempt tested 
4 - Takes <1 second per image on up to 20 images tested
5 - Takes 1-2 seconds, depending on the number and method
6. Since I cannot induce a lag, I am not able to verify a quit failure.

The results are nearly identical on the two devices. 

I have an update: Once I disabled the sync completely (by going to the lightroom page online in browser and choosing delete all synced images) - funny they did not provide any other means of switching the sync off completely via Lightroom UI! So once the sync is completely off - most of the lags are gone, except for one - creating new collections and adding new images to them. All the rest - applying auto tone, adding adaptive presets with auto-generated masks - all started working just fine. 

I must add here that while the sync database is active, putting sync on hold (pause), or letting it complete all tasks (green tick showing in sync status, all sync done) - DOES NOT FIX THE LAGS! Lightroom is still often using a bit more than 100% mac CPU and many operations lag atrociously down to downright freezing the whole app.

I have no idea why nobody is working on this bug, and nobody even condescending to reply here. 

so I guess Adobe gave up on this issue, nobody replying, nobody testing? Amazing!

Just tested the new 14.2 release that Rikk said contains "an update" for this issue, and NO, the bug is still there, glaring and strong. The symtoms are the same, perhaps even worse now, because even when sycn is all done and in "complete" green tick status applying Adaptive presets still lags, alongside with applying Auto settings, updating process version settings, adding pics to albums and collections - ALL STILL LAG. And the CPU usage is also same - while this lagging occurs Lightroom utilizes around 100% of Mac CPU (which means like 1 Processor Core in Mac's crazy CPU activity monitor) while sitting idle and apparently doing nothing (sync all done and complete, no export or other jobs on activity tab). 

It is beyong outrageous and beyond ridiculous that we are still here aFTER MONTHS AND MONTHS of me reporting this issue!

Greetings all, 

A new update for Adobe Photography Products has been released.  The February updates contain an update for this issue. 

If you do not see the update in your Creative Cloud Application, you can refresh it by hitting [Ctrl/Cmd]+[Alt/Opt]+[ R ].

Note: It may take up to 24 hours for your update to be available in your Creative Cloud app.

Thank you for being so patient.

Not only not fixed in 14.1.1 but got worse. Again everything freezes for minutes, Rikk are you there? Time to poke those Quality department engineers. Lightroom with large catalog and lots of albums and AI portrait presets is UNUSABLE!

NOT FIXED in 14.1.1