Synfig currently provides a custom software renderer, which is is not able to take advantage of advanced optimization and hardware acceleration techniques. Porting the renderer to the Cairo graphics library will allow for a faster, more versatile framework.
Condense the Synfig user interface into a single window to provide a simpler, easier workflow for animators.
Synfig currently lacks support for importing sound clips and synchronizing them with the animation. This project would consist of selecting an appropriate audio framework (e.g. gstreamer), integrating it into Synfig, and providing a suitable user interface to synchronize sound and animation.
Support for bones was added in a separate branch of Synfig, but it currently lacks a user interface. This project would involve writing a GUI to edit bones and integrating it into the current development branch of Synfig.