Adam42

An 800x600 image is just under half a million pixels. The magic wand takes about 5 seconds, which is not too bad. A 1024x1024 image is just over a million pixels. With double the pixels you might expect it to take about 10 seconds. It actually takes about 60 seconds. The 2048x2048 image is just over 4 million pixels, and I got bored waiting for it to finish. The photo I found the problem was 20MP but not as bad for performance as the random noise. Selections with the magic wand were taking over a minute though, which is a right pain when you want to play with the tolerance to find a value

The magic wand tool performs badly on some images. Reproduction steps: 1. Create a 1000x1000 image. 2. Use the add noise effect to add some full intensity noise. 3. Select the magic want tool and pick global flood mode, 50% tolerance. 4. Click somewhere on the image, and press finish. 5. It will take about a minute, and use only one CPU core. The same steps complete in a few seconds on an 800x600 image. A 2000x2000 image doesn't finish in a reasonable amount of time. There's some sort of scaling issue here - surely the performance should be proportional to the number of pix