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.