I am using 0.48+devel+12398+35~quantal1 from the inkscape-trunk PPA on Kubuntu 12.10, both with and without kwin compositing. I have been pleased that this version uses less memory and renders complex objects more quickly than the stable version. Keep up the great work!
The problem I have is when dragging an object inside a complex scene, inkscape becomes very unresponsive (and the CPU is pegged during this time). I can tell that some effort has been made to improve this, because for about the first half-second after I start dragging, it is very responsive (so apparently it is not trying to re-draw the entire object or the background with every frame). After this time, though, the frame rate drops to about 0.5Hz and it becomes more or less impossible to move / scale / rotate the object with the mouse. Furthermore, inkscape (or possibly gtk / X) seems to drop mouse events when it is overloaded, so I can't simply move the mouse to its final destination and wait for inkscape to catch up--I have to keep wiggling the mouse to generate new events until the object is in position. The performance is the same when moving objects with the keyboard. In contrast, changing the order of objects (pgup/pgdn) is very responsive.
Is there anything I can do to profile this? Anything I can try to fix it?
I have attached an example svg that demonstrates the problem on my system.
Confirmed on Windows XP, Inkscape trunk revision 12703.
With 0.48.4, moving the rectangle is slow when on the complex path, but performance is not affected when moving outside the complex path.
With r12703, it is significantly slower, and performance is affected everywhere (even on the blank parts of the workspace).