http://bugs.winehq.org/show_bug.cgi?id=21070
--- Comment #5 from Roderick Colenbrander thunderbird2k@gmail.com 2009-12-19 09:59:33 --- I think I know what will help. By default we have font smoothing disabled. Try to set it to enabled (e.g. using winetricks). With smoothing enabled, font rendering is a LOT faster on nvidia.