10 March 2013
http://fbreader.org/ - slower, best user interface (can click on items in table of contents)
http://blog.kowalczyk.info/software/sumatrapdf/free-pdf-reader.html - faster but less usable (can't click on items in table of contents)
Also surprise, surprise, Adobe acrobat is not that bad as a book reader for PDF files ! In the View menu, select the 'Read Mode' option (or Ctrl+H), and voila !
Now for years I was suffering from the default mode of viewing PDF files, which splits up the text into pages; Navigation between the pages is a bit edgy, so longer texts are hard to read that way. Interesting if other people have a similar experience - some useful feature hidden in a behemoth program, and this non obvious feature only makes the whole thing usable.