I'm recently thinking of a new input-method platform, that's python+dbus.

The advantages are, dbus has the python binding, that make it easier to write an IM server daemon with python. In client side, since dbus also has the glib and QT bindings, it also makes it easier to write the input method modules for gtk and QT. For input method developers, writing the input method in python (or plus with C/C++ python extension) is also a nice thing.

How about the performance? No idea, while I think it's worth to have a try and make a prototype.