diff --git a/src/hb-ot-layout-gsubgpos.hh b/src/hb-ot-layout-gsubgpos.hh
index 0246d80e4..04ccefd10 100644
--- a/src/hb-ot-layout-gsubgpos.hh
+++ b/src/hb-ot-layout-gsubgpos.hh
@@ -1003,7 +1003,7 @@ struct hb_accelerate_subtables_context_t :
 
 
 typedef bool (*intersects_func_t) (const hb_set_t *glyphs, unsigned value, const void *data, void *cache);
-typedef void (*intersected_glyphs_func_t) (const hb_set_t *glyphs, const void *data, unsigned value, hb_set_t *intersected_glyphs);
+typedef void (*intersected_glyphs_func_t) (const hb_set_t *glyphs, const void *data, unsigned value, hb_set_t *intersected_glyphs, void *cache);
 typedef void (*collect_glyphs_func_t) (hb_set_t *glyphs, unsigned value, const void *data);
 typedef bool (*match_func_t) (hb_glyph_info_t &info, unsigned value, const void *data);
 
@@ -1052,17 +1052,36 @@ static inline bool intersects_coverage (const hb_set_t *glyphs, unsigned value,
 }
 
 
-static inline void intersected_glyph (const hb_set_t *glyphs HB_UNUSED, const void *data, unsigned value, hb_set_t *intersected_glyphs)
+static inline void intersected_glyph (const hb_set_t *glyphs HB_UNUSED, const void *data, unsigned value, hb_set_t *intersected_glyphs, HB_UNUSED void *cache)
 {
   unsigned g = reinterpret_cast<const HBUINT16 *>(data)[value];
   intersected_glyphs->add (g);
 }
-static inline void intersected_class_glyphs (const hb_set_t *glyphs, const void *data, unsigned value, hb_set_t *intersected_glyphs)
+
+using intersected_class_cache_t = hb_hashmap_t<unsigned, hb_set_t>;
+
+static inline void intersected_class_glyphs (const hb_set_t *glyphs, const void *data, unsigned value, hb_set_t *intersected_glyphs, void *cache)
 {
   const ClassDef &class_def = *reinterpret_cast<const ClassDef *>(data);
-  class_def.intersected_class_glyphs (glyphs, value, intersected_glyphs);
+
+  intersected_class_cache_t *map = (intersected_class_cache_t *) cache;
+
+  hb_set_t *cached_v;
+  if (map->has (value, &cached_v))
+  {
+    intersected_glyphs->union_ (*cached_v);
+    return;
+  }
+
+  hb_set_t v;
+  class_def.intersected_class_glyphs (glyphs, value, &v);
+
+  intersected_glyphs->union_ (v);
+
+  map->set (value, std::move (v));
 }
-static inline void intersected_coverage_glyphs (const hb_set_t *glyphs, const void *data, unsigned value, hb_set_t *intersected_glyphs)
+
+static inline void intersected_coverage_glyphs (const hb_set_t *glyphs, const void *data, unsigned value, hb_set_t *intersected_glyphs, HB_UNUSED void *cache)
 {
   Offset16To<Coverage> coverage;
   coverage = value;
@@ -1516,7 +1535,8 @@ static void context_closure_recurse_lookups (hb_closure_context_t *c,
 					     unsigned value,
 					     ContextFormat context_format,
 					     const void *data,
-					     intersected_glyphs_func_t intersected_glyphs_func)
+					     intersected_glyphs_func_t intersected_glyphs_func,
+					     void *cache)
 {
   hb_set_t *covered_seq_indicies = hb_set_create ();
   for (unsigned int i = 0; i < lookupCount; i++)
@@ -1537,7 +1557,7 @@ static void context_closure_recurse_lookups (hb_closure_context_t *c,
           pos_glyphs.add (value);
           break;
         case ContextFormat::ClassBasedContext:
-          intersected_glyphs_func (&c->parent_active_glyphs (), data, value, &pos_glyphs);
+          intersected_glyphs_func (&c->parent_active_glyphs (), data, value, &pos_glyphs, cache);
           break;
         case ContextFormat::CoverageBasedContext:
           pos_glyphs.set (c->parent_active_glyphs ());
@@ -1554,7 +1574,7 @@ static void context_closure_recurse_lookups (hb_closure_context_t *c,
           input_value = input[seqIndex - 1];
         }
 
-        intersected_glyphs_func (c->glyphs, input_data, input_value, &pos_glyphs);
+        intersected_glyphs_func (c->glyphs, input_data, input_value, &pos_glyphs, cache);
       }
     }
 
@@ -1734,7 +1754,8 @@ struct ContextClosureLookupContext
   ContextClosureFuncs funcs;
   ContextFormat context_format;
   const void *intersects_data;
-  void *cache;
+  void *intersects_cache;
+  void *intersected_glyphs_cache;
 };
 
 struct ContextCollectGlyphsLookupContext
@@ -1757,7 +1778,9 @@ static inline bool context_intersects (const hb_set_t *glyphs,
 {
   return array_is_subset_of (glyphs,
 			     inputCount ? inputCount - 1 : 0, input,
-			     lookup_context.funcs.intersects, lookup_context.intersects_data, lookup_context.cache);
+			     lookup_context.funcs.intersects,
+			     lookup_context.intersects_data,
+			     lookup_context.intersects_cache);
 }
 
 template <typename HBUINT>
@@ -1778,7 +1801,8 @@ static inline void context_closure_lookup (hb_closure_context_t *c,
 				     value,
 				     lookup_context.context_format,
 				     lookup_context.intersects_data,
-				     lookup_context.funcs.intersected_glyphs);
+				     lookup_context.funcs.intersected_glyphs,
+				     lookup_context.intersected_glyphs_cache);
 }
 
 template <typename HBUINT>
@@ -2287,11 +2311,13 @@ struct ContextFormat2_5
     const ClassDef &class_def = this+classDef;
 
     hb_map_t cache;
+    intersected_class_cache_t intersected_cache;
     struct ContextClosureLookupContext lookup_context = {
       {intersects_class, intersected_class_glyphs},
       ContextFormat::ClassBasedContext,
       &class_def,
-      &cache
+      &cache,
+      &intersected_cache
     };
 
     + hb_enumerate (ruleSet)
@@ -2690,7 +2716,8 @@ struct ChainContextClosureLookupContext
   ContextClosureFuncs funcs;
   ContextFormat context_format;
   const void *intersects_data[3];
-  void *cache[3];
+  void *intersects_cache[3];
+  void *intersected_glyphs_cache;
 };
 
 struct ChainContextCollectGlyphsLookupContext
@@ -2717,13 +2744,19 @@ static inline bool chain_context_intersects (const hb_set_t *glyphs,
 {
   return array_is_subset_of (glyphs,
 			     backtrackCount, backtrack,
-			     lookup_context.funcs.intersects, lookup_context.intersects_data[0], lookup_context.cache[0])
+			     lookup_context.funcs.intersects,
+			     lookup_context.intersects_data[0],
+			     lookup_context.intersects_cache[0])
       && array_is_subset_of (glyphs,
 			     inputCount ? inputCount - 1 : 0, input,
-			     lookup_context.funcs.intersects, lookup_context.intersects_data[1], lookup_context.cache[1])
+			     lookup_context.funcs.intersects,
+			     lookup_context.intersects_data[1],
+			     lookup_context.intersects_cache[1])
       && array_is_subset_of (glyphs,
 			     lookaheadCount, lookahead,
-			     lookup_context.funcs.intersects, lookup_context.intersects_data[2], lookup_context.cache[2]);
+			     lookup_context.funcs.intersects,
+			     lookup_context.intersects_data[2],
+			     lookup_context.intersects_cache[2]);
 }
 
 template <typename HBUINT>
@@ -2750,7 +2783,8 @@ static inline void chain_context_closure_lookup (hb_closure_context_t *c,
 		     value,
 		     lookup_context.context_format,
 		     lookup_context.intersects_data[1],
-		     lookup_context.funcs.intersected_glyphs);
+		     lookup_context.funcs.intersected_glyphs,
+		     lookup_context.intersected_glyphs_cache);
 }
 
 template <typename HBUINT>
@@ -3363,13 +3397,15 @@ struct ChainContextFormat2_5
     const ClassDef &lookahead_class_def = this+lookaheadClassDef;
 
     hb_map_t caches[3] = {};
+    intersected_class_cache_t intersected_cache;
     struct ChainContextClosureLookupContext lookup_context = {
       {intersects_class, intersected_class_glyphs},
       ContextFormat::ClassBasedContext,
       {&backtrack_class_def,
        &input_class_def,
        &lookahead_class_def},
-      {&caches[0], &caches[1], &caches[2]}
+      {&caches[0], &caches[1], &caches[2]},
+      &intersected_cache
     };
 
     + hb_enumerate (ruleSet)