Terrible performance on iMac 5K

Hi everyone,

I'm sure many of you noticed that Apple released updates to the iMac line and also announced an iMac Pro line. Both have faster processors, faster storage, and significantly improved graphics cards.

The iMac Pro is overkill for me, but I'm thinking of upgrading to a maxed out iMac 5k, with 4.2 Ghz i7, 2 TB SSD and 32 or 64 GB of RAM. I'm hoping this will resolve the issues I've had with editing photos in LR.

I can still sell my current iMac for $1,500, so the upgrade will cost me (or rather, my business) about $2,500. Seems like a worthy trade up.

I'll report back once I see the results.

Solution I have found beyond just resizing the viewport:

https://www.thnkdev.com/QuickRes/

This standalone mac application allows you both to upsample the display to even further clarity but, more importantly it lets you run lower native resolutions that do not exist as options from the display panel in Apple's system preferences.

Apple just announced that they are working on a new iMac for fall release (very unusual for Apple to "pre-announce" a product; they are trying to show pro users that they still care, apparently).

Here are the rumored features.

I know they are just that—rumored—but assuming the rumor is accurate, will these specs be enough to address the problem we're discussing in this thread with poor performance of the 5k iMac in Lightroom?

I have the exact same problem. My 5K iMac is about 10 months old and whenever I'm using photoshop and illustrator for a couple of hours my entire iMac slows down 500%. It's literally laughable how slow it starts going. Opening a new document or booting illustrator takes 4 full minutes.. I mean come on.. I paid 3K for this...

Adobe FIX THIS

My iMac does a hard reboot almost every time I try to add a photo to a collection in Develop mode by dragging it from the film strip to the Collections list. Lightroom was in the new Reference View now that I think about it. No problem in Library mode for sure but possibly also in other views within the Develop mode. Otherwise slower than on my MacBook Pro Retina and a few times stopped displaying all Lightroom menus and tools leaving only the active picture window but was able to quit Lightroom in orderly fashion. Worked OK after restarting. Oh, one  more thing, on my second monitor (Apple Display Cinema) in two screen mode it displays faint artifacts that look like burned-on phosphor on old-style monitor. Usually a line a few inches long, horizontal, defined on one side (bottom) and fading to image on the other over half and inch or so. The length and position changes from image to image but consistent per image.

This case is the first hard reboot I've gotten on any MacOS or OS X computer. Graphics adapter and Lightroom problem?

macOS Sierra 10.12.2

iMac Retina 5K, Core i5, late 2015 model

8GB

Lightroom 2015.8

Pictures from a TIFF file cropped to about 3500x3500 pixels.

I recently got my iMac (Retina 5K, 27-inch, Late 2015) with 4GHz i7, 32GB 2133 MHz and upgraded graphic card M395X.
I was hoping for new iMacs last october, but … (thanks apple). I have to say, that

the performance of Illustrator is a shame. Just horrible, even without any content on my surface. It is ok, when I open it with lower resolution, as mentioned above.
But also the performance of League of Legends is a shame. I almost feel i got to broken graphics card. It can handle my 2 additional monitors.

I will contact Adobe and Apple support.

I noticed a rumor back in April that the next iMacs will likely feature significantly improved GPUs.

I wonder if that will help? Frustrating to have to buy a new computer to solve this problem, but I typically upgrade every 3-4 years so I'm about due anyhow.

So... 2 weeks ago I  upgraded to a 5K iMac from my 2011 MacBook Pro which was on its last legs. Everything works great.. except for Lightroom. The preview updates were slow as molasses on a feburary morning, and hitting the Before/After keyboard shortcut took between 5 and 7 seconds each time to see what I had done to an image. Overall the LR experience was miserable.

I tried everything under the sun that I've found in these forums. Turn on/off the GPU, optimize and flush everything, move working images to an SSD, build smart previews, build 1 to 1 previews, build smaller previews... etc.

I fired up my old, tired 2011 MBP with an 2.4 i7 and 16gigs of ram that has been my workhorse for years. It ran the latest LR CC 2015 about 3 times as fast as my new 27" 4.0 i7, 16gig, 4gb VRAM, 3TB Fusion drive Retina iMac. What was the difference besides the processor setup?  Both were running El Capitan, both were running the latest version of Adobe CC. Both were actually using the same catalog I copied over from one machine to the other with the files on external SSD drives. The difference was what others here have said...The Retina screen.

So just out of curiosity I changed the display to a non-Retina resolution.... ah hah!

This worked for me, so give it a try:

In  System Preferences --> Display, hold down the Option key while clicking on "Scaled" in the Resolution section. You will see the list of resolution choices. Now down below that box is a checkbox that says "show low resolution modes". I selected 2880 x 1620 (low resolution) mode, which basically kept my resolution but turned off the Retina pixel depth.

Yes.. it isn't as beautifully clear as the Retina resolution was.. but for someone like me who is working on batches of files per day in LR and PS, it sped me back up to where the performance should be.

So until Adobe figures out how to speed up LR to work with a large Retina display, I'll have to keep my screen set at this depth.

Give it a try and let me know if it worked for you!

I can't speak to Lightroom, but we were definitely having Illustrator performance problems on new iMacs and especially Retina laptops: files very slow to open; zooming and panning were taking forever, etc. Thought it might be a redraw preference but instead found this preference item for GPU performance:

Illustrator CC menu item / Preferences / GPU Performance ...

GPU Performance was defaulted to checked. So we UNCHECKed that box and hit OK and performance was back to what we're used to. Just a guess, but thinking that Illustrator is passing some processing over to GPUs and maybe these GPUs can't handle it (or they're already busy with display). Anyway, with that turned off, Illustrator is actually up to speed now. It may be that GPU processing is a good option if you have a separate NVIDIA card or something but on these GPUs it was grinding everything to a halt.

I've given up waiting for a solution...or even someone identifying definitively what the root problem is. Apparently no one at Apple or Adobe wants us to know. As a result I'm going with a windows/NEC solution as much as I'd like to stick with Apple.