I can't speak too much to the question of speed, except to say that my nice laptop from 2012 is sluggish with darktable. My decent desktop from 2017 is fairly fluid. Neither has a graphics card, but a decent graphics card with OpenCL support makes things much more fluid. Waiting a minute for a simple operation is not something I've experienced, and suggests, as they say, that something, somewhere, is wrong.
As another commenter writes, the problem is that darktable must do a crazy lot of math to display the image -- every step of the image editing process. There is a good bit of caching along the way, but at some point, the math must be done.
I can't speak too much to the question of speed, except to say that my nice laptop from 2012 is sluggish with darktable. My decent desktop from 2017 is fairly fluid. Neither has a graphics card, but a decent graphics card with OpenCL support makes things much more fluid. Waiting a minute for a simple operation is not something I've experienced, and suggests, as they say, that something, somewhere, is wrong.
As another commenter writes, the problem is that darktable must do a crazy lot of math to display the image -- every step of the image editing process. There is a good bit of caching along the way, but at some point, the math must be done.