Lightroom Classic CC seems slower than previous Lightroom version it replaced

After editing multiple images on my iMac 27 i7, Lightroom Classic CC slows down considerably. Importing images (copies) doesn't happen any faster than with the previous version Lightroom 2015 - Adobe should be ashamed! They had promised speed boosts! Where are they?

I am using an iMac with a Intel Core i7 @ 3,4 GHz with 32 GB RAM and a NVIDIA GeForce GTX 680MX 2048 MB. In comparison to Lightroom CC (the old one) is the "new", Lightroom CC Classic, ridiculously slow! What have you done to this piece of software. After working on a single image and about 10 steps, the software starts to think about every step. Please do your homework and update the software! I have installed the "old", one again!

Modellname: iMa

Upon the advice of a previous poster, I called Adobe and spent quite a bit of time with him. He helped me reinstall LR2015 which probably saved me some time. The changes he made in Classic didn't help, so I am (happily) back in LR 2015. I had made quite a few changes to my catalog over the four or five days while in Classic, so I had to resync a lot of my folders in 2015.

I will delete Classic, then install it clean without updating my main catalog.  I can experiment with a dummy catalog before committing to it when they release a speed/bug fix.

The tech said I would need to install and use LR Classic to be able to read Nikon D850 raw files. It's on order.

I've the same issues stated before.
I've catalogs with 30k+ images and I've noticed LR CC Classic tends to recreate all the standard previews for the new catalog everytime you access a folder.
The slowdowns could depends on this process, which is CPU time consuming.
Anyway, I've faced a lot of black preview when switching between images or between Libray and Develop module.
Plus it happens when using brush for selective modifies and spot removal: it stops responding for 3-4 seconds.
Closing LR CC Classic sometimes, after half an hour improve the performance a bit.
Anyway is far from anything that can be called fast and efficient.
I've a i7 3820 3.6Ghz (quad core), 32GB DDR3, 256GB SSD, Windows 10.
All the catalogs and previews are on the SSD, images on a separate hard drive.

Thank god it's not just me. I have a new AMD based Ryzen 7 1700X system, with 32GB memory, 1TB SSD drives, Nvidia GTX1080Ti, and the performance of LR Classic CC is appalling, it's unusable. I even tried the trick to limit the number of threads to cores+1 in a .lua file, but it only helped a tiny bit. I'm getting huge freezes, screen going black for up to 20s, even taking 10s to switch to new photo in develop module, sliders unresponsive for up to 30s. It's unusable. LR CC 6 was much much faster. I now have to go to trouble of uninstalling to go back to LR CC 6 or just stop using it and move to C1 and DPP. Turning off the graphics acceleration helped a little with screen blacking out, but nothing else. I can't believe how this was pushed out as ready. It's like a pre-pre-alpha.

I do have these issues with any other program including PS CC 2018

LR Classic CC is really a crap release! Performance is medieval at best. And that is on a Mac Pro 5.1 with 48 Gb of RAM, SSD, 6 core 3,46 Ghz Xeon, dual Radeon R9 290X! A couple of years ago I did a test between a PowerMac G4 DP 533 Mhz and a Mac Pro 1.1 2x2 Core running a number of tests in Photoshop of common tasks like unsharp mask, gaussian blur etc. The G4 was running first PS release support ting dual processors fully in OS X, and the Mac Pro the then latest PS-release. Even though the Mac Pro had something like 12x hardware advantage, the times were similar. There were 3 releases between them. Adobes software (I have been told by e former employer of theirs) is a huge gunk of obsolete code, and very little seems to get fixed. And much of the the old code gets recycled in ew software, like Lightroom inherited a lot from Photoshop and CameraRAW, so did the new version of Premiere etc. One thing… neither LR or PS utilises more than 2 cores on a machine with many cores. I do a lot of video and software like DaVinci Resolve 14 and iFFMPEG use pretty much all they can grab, unless you set them up to do otherwise. Adobe products you cant even set up to use more than two...

In 2018, no compromise should have to be made. No option to work with lesser quality should have to be set. No user should have to change their way to allow Lightroom to work faster. Adobe has not yet figured out software performance. Whether After Effects or Lightroom, Adobe has many many many years to go before their software performs up to hardware capability. A fully spec'd out PC or Mac should be able to use Lightroom flawlessly. Period.

Thanx to everyone testing LR classic performance .. I tried the suggestions you posted .. but If my LR CC 2015 was working quite well, now it has become a nightmare : several seconds of lag between brush strokes or setting change in Develop, LR has become impossible to work with .. OK I have a rather basic machine, but it worked before .. now it doesn't ..

I liked working LR, but do we have to consider alternatives now?

My experience has been somewhat positive so far.

I have an older XEON 6 Core 3.5ghz 64GB ram Windows 10 Pro setup and I found the following

Import 161 Sony A9 Raw files building 1:1 previews and Smart Previews it took 5:28 in LR CC Classic and 9:41 with LR CC

So thats a pretty good improvement IMHO, I also noticed in the Develop Module images loaded much faster especially when I have the enable GPU acceleration turned on.

Wow - what a day and still LIGHTROOM CLASSIC IS THE PITS!!! (and no progress on getting my post processing backlog worked).  I spent nearly 90 mins online in chat with Adobe Support, regarding the severe slowdown and lag in Lightroom Classic I am experiencing (as are so many others).  First the rep told me "we aren't aware of these problems" (when I told him the community support forum is loaded with complaints of the slowdown).  Second, he had me create a new library catalog, saying the problem was that the conversion when it updated was not successful.  At first we tried this with a test catalog and it seemed to fix the lag and slowness.  So, being assured this will be the fix and I would not experience any further problem (and I even demonstrated as we hooked up with remote live desktop takeover), I finished up the chat and ate dinner and sat down to work on my growing backlog.  It started out with great success.  However, VERY QUICKLY (like 8 pictures later) I started noticing some lag developing in the application and in using the brushes (which is where I had the problem originally).  Well as you would expect, it got worse and within 10 mins, I was experiencing 7-10 sec lag in a brush swipe, and that extended to 15 in some instances.  The program kept freezing and the worst part is I started seeing that infamous spinning ball - UGH!!!!!!!  (so here I sit back online trying to get to Adobe to find out if I can revert to LR 6 (in the photography plan) as I NEVER HAD ANY PROBLEM AND ALWAYS HAD SPEED, SPEED, SPEED IN ALL PRIOR LR VERSIONS.  This is absolutely unacceptable.  To make matters worse, I have gone from number 1 in the question to number 2 four times (not sure how that happens), but I am back to number 1 again.  We'll see what happens.  Bad part is I totally rely on LR for my post processing, so I am really in a pickle with my backlog right now. another UGH!!!!!! (would you believe I just went back to number 2 in line again?  I cannot figure how that could happen.  Maybe they count different in Adobeland.  2, 1, 1, 2 or something like that.