Maybe implement a manually refreshed preview mode?

I just started using Darktable and I can already tell that I could never really use it for my everyday workflow because of how slow the slider interface is. I understand (well, I perceive, I don’t really understand it, haha) that rendering live previews from uncompressed raw data takes serious processing and that Darktable is doing higher quality math than Lightroom, etc., so what about making a switch that turns off the live preview and a keyboard shortcut to refresh (or “apply”) it? So instead of continually refreshing the preview as you move a slider you would move one or more sliders to the position you want and then hit command-R (or whatever) to process the preview.

Raw Photo Processor uses this type of interface and, while it takes some time to get used to, it eventually allows you to be much faster. Live updating previews are great for new users, but once you’ve developed a feel for the controls it’s much faster to move some or all of the variables to where you want and then process the preview all in one step. For instance, if I want to adjust white balance using the individual RGB channel gains and know that I want to move red and green up and blue down a little, it’s really tedious to drag or click the sliders into place while the preview stutters along, delaying the movement of the slider. Using a manually refreshed preview you could allow the sliders to be moved smoothly, in much more precise increments, with the mouse wheel (or keyboard) and then refresh the preview all in one step when you’re done and it would be a much faster way of working.

Another perk of working this way is that it’s very much like working in the wet darkroom, but at hyper speed. In the darkroom you make adjustments to whatever variables you need to and then process a new test print to check the results. Beginners need to make a new test print with each incremental adjustment, but experienced printers can look at a test print, make the necessary adjustments and come very close to a final print with the next sheet of paper. Ideally, that’s how I’d like to work in the digital darkroom too!

I know absolutely nothing about coding or anything so I have no idea how complex this would be, but I think it would add a lot to the app. Thoughts appreciated!

What is your hardware like that you find it to be that slow?

I’m on a 5 year old i5, but have plenty of ram, and it isn’t that slow.

I’m on a Late 2015 5k iMac with 32gb of ram. I haven’t used Darktable for awhile and just realized I was still on 2.x. Upgraded to 3.2 and it is better, but still a bit choppy. Part of it might be that I’m working with Sony’s uncompressed Raw files which are quite large compared to some other formats.

Do you know if there’s any way to manually enter values with the keyboard rather than sliding?

Right click on the slider, write the number, enter.

Edit: in general, you might also want to disable heavy modules until the end (like profiled noise reduction)

This is likely your problem, as this is a pretty well known gtk issue.

My main camera is a D850, and I have little issue loading and manipulating the file, but my screen is 1080P.

I’ve got a 2017 5k imac but it’s now a Linux machine. DT runs far better than it did on macos although 3.1 is a bit slower ATM but it’s not bothering me as it’s fast enough, it’s about the same as what DXO photolab was back when I used that.

aha! Thanks! I knew about the precision dragging when you right click, but didn’t realize you could type then too. That’s helpful!