The other day while testing some ideas brought up in a thread here I ran across a pretty annoying behavior of Krita’s that really hurts performance. It shows up more readily on larger images with filter masks on one or more layers.
When you make adjustments to things like blend mode or opacity Krita naively queues up every single change to be done one after another, even when they are no longer relevant. Such as using the slider for opacity, every little tiny bump to that will have to be processed in the order they were made, so if you grabbed the slider and dragged it around and tried to fine tune it down to a specific value, each time you slowed down or changed directions it added another update pass that has to run in full on that layer before the next one is done and the next after that and so on until every single change has had it’s turn. It some times locked up Krita for 10s of seconds before it finally got through them all and I can resume working again.
Krita should probably be a lot more smart about what sort of updates to follow through with and even consider killing an update part way through if that same value has been tweaked again.