Comment # 3 on bug 1019613 from Ismail Donmez

(In reply to Bernhard Wiedemann from comment #2)
> found that commenting out /usr/share/vim/vim74/syntax/yaml.vim:113
> avoids the issue:
> "execute 'syn match yamlBlockMappingKey
> /\s*\zs'.s:ns_plain_out.'\ze\s*:\%(\s\|$\)/ contained '.
> "            \'nextgroup=yamlKeyValueDelimiter'
> 
> so maybe drop or optimize that regexp together with upstream
> to not be O(n^2) or even O(2^n) ?

The problem seems to be the new regexp engine. Since you did the most of the
work, I'll contact upstream to see if it's possible to fix regexp or the
engine.