diff --git a/plugin/sensible.vim b/plugin/sensible.vim
index 2d0404d..b5659e4 100644
--- a/plugin/sensible.vim
+++ b/plugin/sensible.vim
@@ -35,6 +35,11 @@ if maparg('<C-L>', 'n') ==# ''
   nnoremap <silent> <C-L> :nohlsearch<C-R>=has('diff')?'<Bar>diffupdate':''<CR><CR><C-L>
 endif
 
+if &synmaxcol == 3000
+  " Lowering this improves performance in files with long lines.
+  set synmaxcol=500
+endif
+
 set laststatus=2
 set ruler
 set wildmenu