Hi,
I really like Inkscape but there is one thing which frustrate me a lot. It is that raster effects/filters are not buffered so every time I zoom in/ zoom out ore move object all the effects are re-rendered. When I have several objects in the documents with effects applied it becomes really hard to do anything, even moving an object take a long time.
My idea is to add effects/filters buffering. When I apply effect/filter Inkscape renders it in its internal buffer with predefined dpi (this dpi could be property of document). After that this pre-rendered effect/filter can be used whenever object is moved or document is zoomed in or zoomed out.