Regenerate hinting for all fonts

First you have to install TTF Autohinter.

sudo apt-get install libtool automake autoconf qt4-qmake automoc imagemagick inkscape pandoc help2man
cd ~/tools
git clone http://repo.or.cz/ttfautohint.git
cd ttfautohint/
./bootstrap
./configure --with-doc=no
make
make install

Under Ubuntu 12.04, you will need to download and compile harfbuzz:

wget http://www.freedesktop.org/software/harfbuzz/release/harfbuzz-0.9.26.tar.bz2
tar xf harfbuzz-0.9.26.tar.bz2
cd harfbuzz-0.9.26
./configure && make && sudo make install
sudo ldconfig

Under later versions you may try sooner or later

sudo apt-get install harfbuzz

Then it's so simple:

mkdir -p ~/.fonts
for file in $(find /usr -name '*.ttf'); do ttfautohint -c -d -i --hinting-range-min=6 -i $file ~/.fonts/${file##*/}; done
fc-cache -fv