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5 Messages


174 Points

Mon, Dec 4, 2017 4:01 PM

LR Classic CC - extremely slow on 5k displays

Hi, in my point of view Lightroom needs to be rewritten from the ground up. This app could run much, much faster on today's hardware. 

Recenty, with Classic CC release I hoped for some change, but nothing happened here. 

This video I took is perfect example how really slow this app runs on iMac 27" 5K with 100k in library. Scrolling on 5k display has no more that 2-5FPS, but simply dragging LR window to my second screen Apple Cinema Disply 22" makes my exprerience much better with almost smooth with +24FPS.

Adobe could you please explain this to me?

And yes, I've tried all the "performence tips"!

iMac 27 5k - Intel i5 - 3,2GHz - late 2015

macOS 10.13.1




1.4K Messages


24.5K Points

3 years ago

Some basic math: 

Apple 22 Cinema: 1600 x 1024 pixels = 1,638,400
5K Display = 5120 × 2880 Pixels = 14,745,600 pixels  or 9X the number of pixels of a Cinema display

Apple 22 Cinema: Your estimate of 24 FPs
Divide by 9 
2.66 FPS 
5K Display: Your estimate of 2-5 FPS

Hmmm... Same GPU processor? You bet. You said you dragged it onto the adjacent monitor.  9X pixels is roughly 9X slower.  Were you expecting 24 FPS on the 5K? What would be an acceptable frame rate on that monitor given that you are pushing 9 times the information? Those reasonable real-world expectations would be great to include in your post. That said, Adobe continues to leverage improvements in the GPU processing area and speed improvements are planned and being implemented with new releases.  I don't think you will ever see a ground-up rewrite of Lightroom Classic. But, that is merely from my point of view.

BTW, Lightroom was rewritten from the ground up and that new application is Lightroom CC. It is still in the 1.x feature-anemic mode but promises to catch up in many areas. 

5 Messages


174 Points

Excuse me, but what kind of math is that?! According to what you say, it would mean that LR CC would not be able to compute scrolling any faster that 24FPS on this lowres screen. So this will cause this expremely sluggish scrolling on any higher resolution screen while computing more pixels. 

That is totally ridiculous!

Any other app is albe to scroll smoothly any content on 5K screen with almost none CPU/GPU load. So why would not be LR CC capable to do that? 

The only reasly I see is that is just simply badly optimised code that needs to be fixed.