diff --git a/src/OT/Layout/Common/CoverageFormat1.hh b/src/OT/Layout/Common/CoverageFormat1.hh
index adc511e9d..5d68e3d15 100644
--- a/src/OT/Layout/Common/CoverageFormat1.hh
+++ b/src/OT/Layout/Common/CoverageFormat1.hh
@@ -77,9 +77,14 @@ struct CoverageFormat1_3
 
   bool intersects (const hb_set_t *glyphs) const
   {
-    /* TODO Speed up, using hb_set_next() and bsearch()?
-     * Experience with other tables suggest that it would
-     * not speed up though. */
+    if (glyphArray.len > glyphs->get_population () * hb_bit_storage ((unsigned) glyphArray.len) / 2)
+    {
+      for (hb_codepoint_t g = HB_SET_VALUE_INVALID; glyphs->next (&g);)
+        if (get_coverage (g) != NOT_COVERED)
+	  return true;
+      return false;
+    }
+
     for (const auto& g : glyphArray.as_array ())
       if (glyphs->has (g))
         return true;