Use ccache to reduce build time

ccache_help

Install ccache:

In Arch:

$ sudo pacman -S ccache

Or Ubuntu:

$ sudo apt-get install ccache

Then run (only needed once):

$ ccache -M -4g

(size of the cache may vary, I use 4g)

Before building (you can put it in your .bashrc):

$ export USE_CCACHE=1

THen build as usual:

$ . build/envsetup.sh
$ lunch
$ make bacon

It can also be use for building kernel (big improvement):

Use a line like:

$ make 'CC="ccache arm-eabi-gcc"'