I'm using PhantomJS/wkhtmltopdf on Ubuntu 12.04 LTS to convert HTML to PDF and get very strange letter spacing errors. For instance, the internal distance between es and xa seems very random and incorrect.
When I run the exact same code on OS X I don't get these problems which make me think the issue is related to Linux. Also, when I render to PNG it looks fine.
I'm using Microsoft Core Fonts and all fonts get the same kerning issue. For instance xa is always a problem, so I don't think it's a font problem either.
I've tried modifying ~/.fonts.conf according to the advice at those links but it makes no difference.
I'm quite stuck on ideas on how to solve this.