P: Slow performance on Xeon CPUs

I have a 4k display with an 8 core i-7 with 24GB RAM and I am basically dead in the water - I have been editing the same wedding since last Wednesday (5 days so far - 1800 .nef's!)

I can not live like this!  I will have to go back to using the Photoshop Image processor if this does not change soon!

I started having slow performance issues around August of this year - 2016 - It was after an update was installed, but I do not recall what the version number was!

Actually the mobile 4790 - I read it is somewhat of a wash.

I'm on a 17" laptop, no dual displays, WIN 10 Anniversary edition and the latest update to LR 6. It's been creeping since the spring starting on the old machine which had been upgraded over and over. I thought the brand new build and hardware would change things.

One thing did help a little after reading this thread yesterday was turning off the GPU on my Invidia 1070 video card for Lightroom. I used the Invidia settings. It still lags a little when going from one photo to the next or pasting settings or adjustment brushing any amount at all, but not the four or five seconds it was taking.

In all, we shouldn't even be having this conversation. LR has an issue that we should not have to tweak away.

According to PassMark's benchmarks the i7-6700HQ (8,023) is a lower performance processor than your previous i7-4790 (9,995). Also moving caches to a separate SSD has very little affect on LR's performance. What exact version of LR are you using, what OS version, what is your monitor's resolution, and are you using dual-displays?

I upgraded my machine from an I7 4790 and 16gb of ram with a 1tb SSD drive to one with an I7 6700HQ 64gb RAM and two 1tb SSD drives - keeping the cache on a separate drive. I did this because I thought I had worn out the old machine because LR CC had started to run so slowly. It runs just as slowly on the new machine and it is becoming extremely frustrating.

When will Adobe address this issue?

I did some tests and can confirm this behaviour:
using a 6 (12) core i7 machine with a 4k display makes Lightroom nearly compleately non-usable!
reducing the used cores by the described command above and reducing the display resolution speeds LR up.
In my eyes it is absolutely inacceptable that the leading application for photography pros shows this behaviour. It's exactly this group of users who will use 4k displays and high performance PCs on which LR fails and slows down rapidly!

Same problem Dawid.. I have Macbook Pro I5 2.9Ghz SSD 512, Ram 8go.. 

i7 -3770k w Win10 here with 16 GB RAM, Sapphire 7850 @ 1920x1200; latest Lightroom 6.7 on fast SSD with plenty of free space. Same issues: over about 20 spot adjustments and brushes on a single photography LR starts lagging terribly.

Using a brush it takes up to 20/30 seconds just for the red overlay to display over the area I just brushed. Same for additional spot tool edits. LR basically becomes unusable.
Hw acceleration on or off does not make any significant difference.

Frankly speaking it is unacceptable for a professional photography software as LR is supposed to be.

Even more it seems there is no developer feedback on this matter.
Not exactly the type of support you'd expect.

The above link references performance issues with a Xeon 6-core system that only started after updating from LR 6.6.1 to 6.7. Rolling back to 6.6.1 resolved the issues for this user.