diff --git a/src/libponyc/type/subtype.c b/src/libponyc/type/subtype.c
index 6dc89094bb0..a7e56ed5ef3 100644
--- a/src/libponyc/type/subtype.c
+++ b/src/libponyc/type/subtype.c
@@ -769,10 +769,6 @@ static bool is_nominal_sub_structural(ast_t* sub, ast_t* super,
   ast_t* sub_def = (ast_t*)ast_data(sub);
   ast_t* super_def = (ast_t*)ast_data(super);
 
-  // Add an assumption: sub <: super
-  if(push_assume(sub, super, opt))
-    return true;
-
   bool ret = true;
 
   ast_t* sub_typeargs = ast_childidx(sub, 2);
@@ -838,7 +834,6 @@ static bool is_nominal_sub_structural(ast_t* sub, ast_t* super,
     super_member = ast_sibling(super_member);
   }
 
-  pop_assume();
   return ret;
 }
 
@@ -926,14 +921,8 @@ static bool is_entity_sub_trait(ast_t* sub, ast_t* super,
   return true;
 }
 
-static bool is_struct_sub_trait(ast_t* sub, ast_t* super, check_cap_t check_cap,
-  errorframe_t* errorf, pass_opt_t* opt)
+static bool is_struct_sub_trait(ast_t* sub, ast_t* super, errorframe_t* errorf)
 {
-  (void)check_cap;
-
-  if(check_assume(sub, super, opt))
-    return true;
-
   struct_cant_be_x(sub, super, errorf, "a trait");
   return false;
 }
@@ -995,7 +984,7 @@ static bool is_nominal_sub_trait(ast_t* sub, ast_t* super,
       return is_entity_sub_trait(sub, super, check_cap, errorf, opt);
 
     case TK_STRUCT:
-      return is_struct_sub_trait(sub, super, check_cap, errorf, opt);
+      return is_struct_sub_trait(sub, super, errorf);
 
     case TK_TRAIT:
       return is_trait_sub_trait(sub, super, check_cap, errorf, opt);
@@ -1013,8 +1002,13 @@ static bool is_nominal_sub_trait(ast_t* sub, ast_t* super,
 static bool is_nominal_sub_nominal(ast_t* sub, ast_t* super,
   check_cap_t check_cap, errorframe_t* errorf, pass_opt_t* opt)
 {
+  // Add an assumption: sub <: super
+  if(push_assume(sub, super, opt))
+    return true;
+
   // N k <: N' k'
   ast_t* super_def = (ast_t*)ast_data(super);
+  bool ret = false;
 
   switch(ast_id(super_def))
   {
@@ -1022,19 +1016,23 @@ static bool is_nominal_sub_nominal(ast_t* sub, ast_t* super,
     case TK_STRUCT:
     case TK_CLASS:
     case TK_ACTOR:
-      return is_nominal_sub_entity(sub, super, check_cap, errorf, opt);
+      ret = is_nominal_sub_entity(sub, super, check_cap, errorf, opt);
+      break;
 
     case TK_INTERFACE:
-      return is_nominal_sub_interface(sub, super, check_cap, errorf, opt);
+      ret = is_nominal_sub_interface(sub, super, check_cap, errorf, opt);
+      break;
 
     case TK_TRAIT:
-      return is_nominal_sub_trait(sub, super, check_cap, errorf, opt);
+      ret = is_nominal_sub_trait(sub, super, check_cap, errorf, opt);
+      break;
 
-    default: {}
+    default:
+      pony_assert(0);
   }
 
-  pony_assert(0);
-  return false;
+  pop_assume();
+  return ret;
 }
 
 static bool is_nominal_sub_typeparam(ast_t* sub, ast_t* super,
@@ -1515,7 +1513,7 @@ static bool is_arrow_sub_x(ast_t* sub, ast_t* super, check_cap_t check_cap,
   return false;
 }
 
-bool is_x_sub_x(ast_t* sub, ast_t* super, check_cap_t check_cap,
+static bool is_x_sub_x(ast_t* sub, ast_t* super, check_cap_t check_cap,
   errorframe_t* errorf, pass_opt_t* opt)
 {
   pony_assert(sub != NULL);
diff --git a/src/libponyrt/actor/messageq.c b/src/libponyrt/actor/messageq.c
index 04689f3405b..a91f090b324 100644
--- a/src/libponyrt/actor/messageq.c
+++ b/src/libponyrt/actor/messageq.c
@@ -80,15 +80,14 @@ bool ponyint_messageq_push(messageq_t* q, pony_msg_t* m)
 pony_msg_t* ponyint_messageq_pop(messageq_t* q)
 {
   pony_msg_t* tail = q->tail;
-  pony_msg_t* next = atomic_load_explicit(&tail->next, memory_order_acquire);
-#ifdef USE_VALGRIND
-  ANNOTATE_HAPPENS_AFTER(&tail->next);
-#endif
+  pony_msg_t* next = atomic_load_explicit(&tail->next, memory_order_relaxed);
 
   if(next != NULL)
   {
     q->tail = next;
+    atomic_thread_fence(memory_order_acquire);
 #ifdef USE_VALGRIND
+    ANNOTATE_HAPPENS_AFTER(&tail->next);
     ANNOTATE_HAPPENS_BEFORE_FORGET_ALL(tail);
 #endif
     ponyint_pool_free(tail->index, tail);
diff --git a/src/libponyrt/gc/cycle.c b/src/libponyrt/gc/cycle.c
index 41a94287042..00d3a9a217f 100644
--- a/src/libponyrt/gc/cycle.c
+++ b/src/libponyrt/gc/cycle.c
@@ -675,22 +675,25 @@ static void final(pony_ctx_t* ctx, pony_actor_t* self)
   // Find block messages and invoke finalisers for those actors
   pony_msg_t* msg;
 
-  while((msg = ponyint_messageq_pop(&self->q)) != NULL)
+  do
   {
-    if(msg->id == ACTORMSG_BLOCK)
+    while((msg = ponyint_messageq_pop(&self->q)) != NULL)
     {
-      block_msg_t* m = (block_msg_t*)msg;
+      if(msg->id == ACTORMSG_BLOCK)
+      {
+        block_msg_t* m = (block_msg_t*)msg;
 
-      if(m->delta != NULL)
-        ponyint_deltamap_free(m->delta);
+        if(m->delta != NULL)
+          ponyint_deltamap_free(m->delta);
 
-      if(!ponyint_actor_pendingdestroy(m->actor))
-      {
-        ponyint_actor_setpendingdestroy(m->actor);
-        ponyint_actor_final(ctx, m->actor);
+        if(!ponyint_actor_pendingdestroy(m->actor))
+        {
+          ponyint_actor_setpendingdestroy(m->actor);
+          ponyint_actor_final(ctx, m->actor);
+        }
       }
     }
-  }
+  } while(!ponyint_messageq_markempty(&self->q));
 
   detector_t* d = (detector_t*)self;
   size_t i = HASHMAP_BEGIN;
@@ -707,6 +710,14 @@ static void final(pony_ctx_t* ctx, pony_actor_t* self)
       ponyint_actor_final(ctx, view->actor);
     }
   }
+
+  i = HASHMAP_BEGIN;
+  while((view = ponyint_viewmap_next(&d->deferred, &i)) != NULL)
+    ponyint_viewmap_remove(&d->deferred, view);
+
+  ponyint_viewmap_destroy(&d->deferred);
+  ponyint_viewmap_destroy(&d->views);
+  ponyint_perceivedmap_destroy(&d->perceived);
 }
 
 #ifndef NDEBUG
@@ -908,6 +919,8 @@ void ponyint_cycle_terminate(pony_ctx_t* ctx)
 {
   pony_become(ctx, cycle_detector);
   final(ctx, cycle_detector);
+  ponyint_destroy(cycle_detector);
+  cycle_detector = NULL;
 }
 
 bool ponyint_is_cycle(pony_actor_t* actor)
diff --git a/src/libponyrt/sched/mpmcq.c b/src/libponyrt/sched/mpmcq.c
index 521e5af3909..dba331891b5 100644
--- a/src/libponyrt/sched/mpmcq.c
+++ b/src/libponyrt/sched/mpmcq.c
@@ -93,10 +93,14 @@ void ponyint_mpmcq_push_single(mpmcq_t* q, void* data)
 void* ponyint_mpmcq_pop(mpmcq_t* q)
 {
 #ifdef PLATFORM_IS_X86
-  PONY_ABA_PROTECTED_PTR(mpmcq_node_t) cmp = bigatomic_load_explicit(&q->tail,
-    memory_order_relaxed);
+  PONY_ABA_PROTECTED_PTR(mpmcq_node_t) cmp;
   PONY_ABA_PROTECTED_PTR(mpmcq_node_t) xchg;
   mpmcq_node_t* tail;
+  // Load the tail non-atomically. If object and counter are out of sync, we'll
+  // do an additional CAS iteration which isn't less efficient than doing an
+  // atomic initial load.
+  cmp.object = q->tail.object;
+  cmp.counter = q->tail.counter;
 #else
   mpmcq_node_t* tail = atomic_load_explicit(&q->tail, memory_order_relaxed);
 #endif
diff --git a/test/libponyc/type_check_subtype.cc b/test/libponyc/type_check_subtype.cc
index b269df9da76..6c604559031 100644
--- a/test/libponyc/type_check_subtype.cc
+++ b/test/libponyc/type_check_subtype.cc
@@ -1033,3 +1033,22 @@ TEST_F(SubTypeTest, IsBeSubFunTag)
 
   pass_opt_init(&opt);
 }
+
+
+TEST_F(SubTypeTest, IsTypeparamSubIntersect)
+{
+  const char* src =
+    "class B\n"
+    "  fun f[A: (I32 & Real[A])](a: A, b: (I32 & Real[A])) =>\n"
+    "    None";
+
+  TEST_COMPILE(src);
+
+  pass_opt_t opt;
+  pass_opt_init(&opt);
+
+  ASSERT_TRUE(is_subtype(type_of("a"), type_of("b"), NULL, &opt));
+  ASSERT_TRUE(is_subtype(type_of("b"), type_of("a"), NULL, &opt));
+
+  pass_opt_init(&opt);
+}