New knob: g:syntastic_full_redraws.

doc/syntastic.txt

@@ -348,6 +348,13 @@ statusline: >
 If the buffer had 2 warnings, starting on line 5 then this would appear: >
     [Warn: 5 #2]
 <
+                                                    *'syntastic_full_redraws'*
+Default: 0 in GUI Vim and MacVim, 1 otherwise
+Controls whether syntastic calls |:redraw| or |:redraw!| for screen redraws.
+Changing it can in principle make screen redraws smoother, but it can also
+cause screen flicker, or ghost characters.  Leaving it to the default should
+be safe.
+
                                                            *'syntastic_debug'*
 Default: 0
 Set this to 1 to enable debugging: >

plugin/syntastic.vim

@@ -56,6 +56,10 @@ if !exists("g:syntastic_filetype_map")
     let g:syntastic_filetype_map = {}
 endif
 
+if !exists("g:syntastic_full_redraws")
+    let g:syntastic_full_redraws = !( has('gui_running') || has('gui_macvim'))
+endif
+
 let s:registry = g:SyntasticRegistry.Instance()
 let s:notifiers = g:SyntasticNotifiers.Instance()
 let s:modemap = g:SyntasticModeMap.Instance()
@@ -229,10 +233,10 @@ endfunction
 "However, on some versions of gvim using `redraw!` causes the screen to
 "flicker - so use redraw.
 function! s:Redraw()
-    if has('gui_running') || has('gui_macvim')
-        redraw
-    else
+    if g:syntastic_full_redraws
         redraw!
+    else
+        redraw
     endif
 endfunction