Zwei ganz konkrete Tipps:
LCD-Filter einschalten
# ln -s ../conf.avail/11-lcdfilter-default.conf /etc/fonts/conf.d/
Autohinter für Cantarell erzwingen
# cat > /etc/fonts/conf.d/21-cantarell-hinting.conf << EOF
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE fontconfig SYSTEM "../fonts.dtd">
<fontconfig>
<!-- Force the autohinter for Cantarell, as it does not have TT hinting -->
<match target="font">
<test name="family" compare="eq" ignore-blanks="true">
<string>Cantarell</string>
</test>
<edit name="autohint">
<bool>true</bool>
</edit>
</match>
</fontconfig>
EOF