Here is something to try if Lightroom CC (version 6) is REALLY slow for you.Getting straight to the point, if Lightroom CC 2015 is so slow it is really not even usable, try disabling the GPU acceleration in the software:
- Choose Edit > Preferences (Windows) or Lightroom > Preferences (Mac OS).
- On the Performance tab un-check the “Use Graphics Processor” option
- Restart Lightroom
What does this do?
It makes Lr CC 2015 work more like Lr 5, sidestepping what was supposed to be a significant enhancement to improve the performance of the sliders and other tools in the Develop module – especially for 4K and 5K high resolution displays. For some having this feature enabled works, making many things in the Develop module go significantly faster. If you want some more technical details, check out this Adobe forum post. However, it seems that there are many combinations of factors that make it not work well, so disabling the new processing feature may help you get back to the speeds you saw in Lightroom 5.
Why GPU Acceleration?
If you already know what a GPU is and does, skip this section. Although I could drone on and on about how it is we got here, instead of nerding out completely see if this helps. There are two basic processing units in your computer that do work: the graphics processing unit (GPU) and central processing unit (CPU). Both are incredible engineering accomplishments that we are all very lucky to have in our lives, even though I am sure many of you feel like you want to throw your computer out the window and watch it burst into a million pieces at times. The GPU is primarily supposed to control the pixels on your screen. The CPU does everything else. In order to draw those pixels really fast so that you can watch movies, play games, or edit photos, the GPU has specifically been engineered to be seriously good at math. Far more efficient at doing huge quantities of math better than the CPU.
When software needs to do a lot of math, if it can give that to the GPU to do then it can get the results back much faster and speed things up versus using the CPU to do that work. Most of the functions in the Develop module in Lightroom need to do a lot of math. Perfect! Sounds like a no-brainer, right? Get the Adobe developers to change Lightroom and have it send that math processing over to the GPU and we all get faster sliders/brushes. Trouble is, developers have to do some special and specific things to make the software use the GPU this way. It is pretty complicated to switch from CPU to GPU for math, and as this Lightroom release has shown, it is easy to get it wrong. Plus, sending the data over to the GPU involves some overhead to take it away from the CPU. Although not much like it actually works, you can think of it a little like having to copy the work that needs to be done from the CPU and pasting it to the GPU for work. Imagine how long that takes to do with the massive photo files we are dealing with. GPU acceleration isn't a silver bullet, there are trade-offs.
Why is it Enabled if it Doesn't Work?
A fair question to be sure. Why would Lightroom default to enabling GPU acceleration if it is broken on so many computers? Adobe engineers tried to make this smart for us. They know most photographers aren't into the bits and bytes going on with their computer and software. The default option is king as most people never change any configuration options from what is delivered. So, they built a test into Lightroom CC 2015 so that when it is first launched it checks to see if the GPU in your computer is one that would make things faster. If your computer passes that test on start up, this new functionality is automatically enabled. Unfortunately, it seems the test may not be comprehensive enough and the option is being enabled on systems that don't actually work well with it turned on.
Should Adobe Give Up on GPU?
No way! I am in complete agreement that Adobe engineers need to tap into the GPU in order to make the develop module faster – especially when we photographers are using displays that are higher resolution than HD (if you are not, you are missing out on a much better experience and need to check out this Photo Taco episode). Game developers have been doing this for years, which is why it is that the GPUs have been so specifically engineered to do huge amounts of math so well. It is absolutely the right solution to the problem and in the long-term is going to make things work a lot faster.
I think the issues we are seeing in this release of Lightroom CC 2015 is nothing more than a version 1 implementation of something that is truly hard to do. Not only is it tough to get the coding right to use the GPU instead of the CPU, think of all the different makes/models of computers out there in the world. There are GPUs from many different manufacturers (ATI/AMD, Nvidia, and Intel are the biggest), and lots of different models from each manufacturer. Each video card has a somewhat unique set of capabilities. Since it is impossible for a developer to deal with all of that variation, in 2006 the OpenCL standard was created to make them all look roughly the same to the developer – yet some support OpenCL better than others.
Maybe the sales team pushed to have the product released a little before the engineers actually got it ready. In my day job as a software developer in the financial industry I can attest to that happening as more of the rule rather than an exception. Who knows why there seems to be so many issues with this release related to GPU acceleration, but I am confident that this is the right direction to take the product and it will be really good soon.
Don't get me wrong, I am not excusing or giving Adobe on a pass for a very problematic release. Many are finding Lightroom CC 2015 to be pretty much unusable. I would expect some trouble, but not to the scale I am seeing it be reported. The Adobe forums are ablaze with fiery posts from high end and knowledgeable users telling Adobe this release is junk. No way that should be happening. I am saying it is worth being a little patient here because the pain will be worth it. If Lr CC 2015 is not working for you use Lr 5 until you get the all clear from us here at improvephotography.com.
Give Adobe Feedback
If you want to make one of those fiery posts to the Adobe team, you are certainly welcome to do so, but I recommend you take a breath and slow down for a second. Ranting when you are looking for help doesn't end up being very helpful in pretty much any context, and a small does of constraint in your feedback will be much better received. However, I think it is really important that as many as possible provide feedback so that Adobe hears the issues and doesn't see the complaints as a small group of people.
You can provide your feedback on the release regarding speed issues or even features that they missed at the Official Feature Request/Bug Report Forum at https://feedback.photoshop.com/photoshop_family
Stay tuned for more information and reviews of Lightroom CC as the IP team pounds away at the product and offers real-world advice.