Comment 3 for bug 506287

@JazzyNico - could it be related to this?

Revision 7446 by buliabyak, 2009-03-09 00:38:46
switch opacity and blur sliders to delayed update, which makes them much more resposive and easier to handle; also, remove the old workaround for gtk crash which is no more, allowing interruptibility and thus also improving responsiveness
files modified:
           src/ui/widget/filter-effect-chooser.cpp
           src/ui/widget/object-composite-settings.cpp
<http://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/revision/7446>

'old workaround for gtk crash' seems to refer to
Bug #168044 in Inkscape: “crash adjusting slider when spinbutton has focus (GTK bug?)”:
<https://bugs.edge.launchpad.net/inkscape/+bug/168044>