Question

I have tried the usual approaches, and have read :help tex.vim
(see : http://vimdoc.sourceforge.net/htmldoc/syntax.html )

I’ve taken a brief look at syntax/tex.vim, but can’t see how to disable it without rebuilding vim without folding. I’m sick of hitting ‘zE’.

Lines I’ve tried in my .vimrc:

set foldlevel=manual
set foldlevelstart=99
let g:tex_fold_enabled=0

Answer 1

Just noticed that there are variables to control folding in vim-latex-suite, at least as of v1.6 of the plugin. The functionality is documented here:
http://vim-latex.sourceforge.net/documentation/latex-suite.html#latex-folding

In short you should be able to change three global variables to get rid of all folding:

 :let Tex_FoldedSections=""
 :let Tex_FoldedEnvironments=""
 :let Tex_FoldedMisc=""

That should get rid of all folding. If you want to disable some folding but not all then you can control things by setting the appropriate values for each variable, as described in the documentation link above. Hope that helps.