Update runtime files.

runtime/doc/syntax.txt

@@ -1,4 +1,4 @@
-*syntax.txt*	For Vim version 7.3.  Last change: 2013 Mar 01
+*syntax.txt*	For Vim version 7.3.  Last change: 2013 Mar 13
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -2928,6 +2928,35 @@ if any, is the text at the top of the screen supposed to be in?).
 Another cause of slow highlighting is due to syntax-driven folding; see
 |tex-folding| for a way around this.
 
+								*g:tex_fast*
+
+Finally, if syntax highlighting is still too slow, you may set >
+
+	:let g:tex_fast= ""
+
+in your .vimrc.  Used this way, the g:tex_fast variable causes the syntax
+highlighting script to avoid defining any regions and associated
+synchronization.  The result will be much faster syntax highlighting; the
+price: you will no longer have as much highlighting or any syntax-based
+folding, and you will be missing syntax-based error checking.
+
+You may decide that some syntax is acceptable; you may use the following table
+selectively to enable just some syntax highlighting: >
+
+    b : allow bold and italic syntax
+    c : allow texComment syntax
+    m : allow texMatcher syntax (ie. {...} and [...])
+    M : allow texMath syntax
+    p : allow parts, chapter, section, etc syntax
+    r : allow texRefZone syntax (nocite, bibliography, label, pageref, eqref)
+    s : allow superscript/subscript regions
+    S : allow texStyle syntax
+    v : allow verbatim syntax
+    V : allow texNewEnv and texNewCmd syntax
+<
+As an example, let g:tex_fast= "M" will allow math-associated highlighting
+but suppress all the other region-based syntax highlighting.
+
 					    *tex-morecommands* *tex-package*
  Tex: Want To Highlight More Commands? ~
 
@@ -3822,7 +3851,7 @@ s-{nr}	start of the matched pattern plus {nr} chars to the left
 e	end of the matched pattern
 e+{nr}	end of the matched pattern plus {nr} chars to the right
 e-{nr}	end of the matched pattern plus {nr} chars to the left
-{nr}	(for "lc" only): start matching {nr} chars to the left
+{nr}	(for "lc" only): start matching {nr} chars right of the start
 
 Examples: "ms=s+1", "hs=e-2", "lc=3".