Gero Mudersbach wrote:
Dear Inkscape developers,
first of all I wish to thank you for your great work, Inkscape is extremely useful!
One thing I noticed is that using blur and sometimes opacity makes Inkscape behave slow. It's not only when moving / scaling objects that have blur or opacity values applied but also the whole document editing seems to be slower then. It would be great if these features could be optimized in one of the next versions. Please let me know if I should file a bug report on this request.
Blur is to some degree inherently slow, and Inkscape's implementation is already pretty fast, but obviously it's always possible to make things even faster. For example, one thing for which Inkscape has some preliminary support is multi-threading. On a machine with multiple cores Inkscape can take advantage of this to divide the work of blurring over multiple cores.
If you feel that blur is too slow for your work, be sure to file a feature request. And preferably include some (simple) example of a situation that is too slow for you.
As for opacity, this is more surprising. Theoretically it shouldn't be much slower than no opacity (in both cases the different layers are blended using more or less the same code). If you can provide any example file(s)+action(s) that show a clear difference in speed of the interface, please file a bug report as soon as possible.