Frankly, the size of the library and executable is down in the noise as well, and isn't really my point.
IPC and context switching is blazing fast in Linux already - any improvement in IPC is down in the sub-millisecond level, and is not noticeable by humans. And given how Dbus seems to be used, it seems like it's mostly on the human scale of things.
So I'm really at a loss to figure out what they are trying to fix here. If they're seeing some really slow response times from some events, then I find it extremely hard to believe that improving the IPC by a factor of 1.8x (or honestly, even 10x) is going to make any _noticeable_ difference at all.
So: are they really looking at the right thing? Is IPC truly the bottleneck and the thing causing whatever perceived slowness they are trying to fix? Or, are they parsing XML at runtime, which is notoriously slow? Or something like that?