Feature request: better compile times?

A small GTK example program built with cppgir takes 15 seconds to compile:

main-cppgir.cpp

real    0m14.742s
user    0m13.531s
sys     0m0.948s

This is an order of magnitude slower than gtkmm:

main-gtkmm.cpp

real    0m1.695s
user    0m1.480s
sys     0m0.150s

The difference is that in gtkmm you can include just the headers you need (<gtkmm/widget.h>), while in cppgir you have to include everything (<gtk/gtk.hpp>). Is there anything that can be done about this?