diff --git a/include/pocketpy/namedict.h b/include/pocketpy/namedict.h
index 941a4655..6eafc072 100644
--- a/include/pocketpy/namedict.h
+++ b/include/pocketpy/namedict.h
@@ -13,89 +13,6 @@ constexpr T default_invalid_value(){
     else return Discarded();
 }
 
-#define PK_SMALL_NAME_DICT_CAPACITY 6
-#define PK_SMALL_NAME_DICT_LOOP(B) for(int i=0; i<PK_SMALL_NAME_DICT_CAPACITY; i++) { B }
-
-struct A{
-    uint16_t k;
-    PyVar v;
-};
-
-template<typename V>
-struct SmallNameDict{
-    using K = StrName;
-    static_assert(is_pod_v<V>);
-
-    bool _is_small;
-    uint16_t _size;
-    K _keys[PK_SMALL_NAME_DICT_CAPACITY];
-    V _values[PK_SMALL_NAME_DICT_CAPACITY];
-
-    SmallNameDict(): _is_small(true), _size(0) {}
-
-    bool try_set(K key, V val){
-        PK_SMALL_NAME_DICT_LOOP(
-            if(_keys[i] == key){ _values[i] = val; return true; }
-        )
-
-        if(_size == PK_SMALL_NAME_DICT_CAPACITY) return false;
-        if(_keys[_size].empty()){
-            _keys[_size] = key;
-            _values[_size] = val;
-            _size++;
-            return true;
-        }
-
-        PK_SMALL_NAME_DICT_LOOP(
-            if(_keys[i].empty()){
-                _keys[i] = key;
-                _values[i] = val;
-                _size++;
-                return true;
-            }
-        )
-        PK_UNREACHABLE()
-    }
-
-    V try_get(K key) const {
-        PK_SMALL_NAME_DICT_LOOP(
-            if(_keys[i] == key) return _values[i];
-        )
-        return default_invalid_value<V>();
-    }
-
-    V* try_get_2(K key) {
-        PK_SMALL_NAME_DICT_LOOP(
-            if(_keys[i] == key) return &_values[i];
-        )
-        return nullptr;
-    }
-
-    bool del(K key){
-        PK_SMALL_NAME_DICT_LOOP(
-            if(_keys[i] == key){ _keys[i] = StrName(); _size--; return true; }
-        )
-        return false;
-    }
-
-    template<typename Func>
-    void apply(Func func) const {
-        PK_SMALL_NAME_DICT_LOOP(
-            if(!_keys[i].empty()) func(_keys[i], _values[i]);
-        )
-    }
-
-    void clear(){
-        PK_SMALL_NAME_DICT_LOOP(
-            _keys[i] = StrName();
-        )
-        _size = 0;
-    }
-
-    uint16_t size() const { return _size; }
-    uint16_t capacity() const { return PK_SMALL_NAME_DICT_CAPACITY; }
-};
-
 template<typename T>
 struct NameDictItem{
     StrName first;
@@ -103,14 +20,13 @@ struct NameDictItem{
 };
 
 template<typename T>
-struct LargeNameDict {
-    PK_ALWAYS_PASS_BY_POINTER(LargeNameDict)
+struct NameDictImpl {
+    PK_ALWAYS_PASS_BY_POINTER(NameDictImpl)
 
     using Item = NameDictItem<T>;
-    static constexpr uint16_t kInitialCapacity = 32;
+    static constexpr uint16_t kInitialCapacity = 16;
     static_assert(is_pod_v<T>);
 
-    bool _is_small;
     float _load_factor;
     uint16_t _size;
 
@@ -130,11 +46,11 @@ while(!_items[i].first.empty()) {           \
 
 #define HASH_PROBE_0 HASH_PROBE_1
 
-    LargeNameDict(float load_factor=PK_INST_ATTR_LOAD_FACTOR): _is_small(false), _load_factor(load_factor), _size(0) {
+    NameDictImpl(float load_factor=PK_INST_ATTR_LOAD_FACTOR): _load_factor(load_factor), _size(0) {
         _set_capacity_and_alloc_items(kInitialCapacity);
     }
 
-    ~LargeNameDict(){ free(_items); }
+    ~NameDictImpl(){ free(_items); }
 
     uint16_t size() const { return _size; }
     uint16_t capacity() const { return _capacity; }
@@ -234,6 +150,22 @@ while(!_items[i].first.empty()) {           \
         }
     }
 
+    bool contains(StrName key) const {
+        bool ok; uint16_t i;
+        HASH_PROBE_0(key, ok, i);
+        return ok;
+    }
+
+    T operator[](StrName key) const {
+        T val = try_get_likely_found(key);
+#if PK_DEBUG_EXTRA_CHECK
+        if(val == default_invalid_value<T>()){
+            throw std::runtime_error(_S("NameDict key not found: ", key.escape()).str());
+        }
+#endif
+        return val;
+    }
+
     pod_vector<StrName> keys() const {
         pod_vector<StrName> v;
         for(uint16_t i=0; i<_capacity; i++){
@@ -243,6 +175,14 @@ while(!_items[i].first.empty()) {           \
         return v;
     }
 
+    pod_vector<NameDictItem<T>> items() const{
+        pod_vector<NameDictItem<T>> v;
+        apply([&](StrName key, T val){
+            v.push_back(NameDictItem<T>{key, val});
+        });
+        return v;
+    }
+
     void clear(){
         for(uint16_t i=0; i<_capacity; i++){
             _items[i].first = StrName();
@@ -254,90 +194,6 @@ while(!_items[i].first.empty()) {           \
 #undef HASH_PROBE_1
 };
 
-template<typename V>
-struct NameDictImpl{
-    PK_ALWAYS_PASS_BY_POINTER(NameDictImpl)
-
-    union{
-        SmallNameDict<V> _small;
-        LargeNameDict<V> _large;
-    };
-
-    NameDictImpl(): _small() {}
-    NameDictImpl(float load_factor): _large(load_factor) {}
-
-    bool is_small() const{
-        const bool* p = reinterpret_cast<const bool*>(this);
-        return *p;
-    }
-
-    void set(StrName key, V val){
-        if(is_small()){
-            bool ok = _small.try_set(key, val);
-            if(!ok){
-                SmallNameDict<V> copied(_small);
-                // move to large name dict
-                new (&_large) LargeNameDict<V>();
-                copied.apply([&](StrName key, V val){
-                    _large.set(key, val);
-                });
-                _large.set(key, val);
-            }
-        }else{
-            _large.set(key, val);
-        }
-    }
-
-    uint16_t size() const{ return is_small() ?_small.size() : _large.size(); }
-    uint16_t capacity() const{ return is_small() ?_small.capacity() : _large.capacity(); }
-    V try_get(StrName key) const { return is_small() ?_small.try_get(key) : _large.try_get(key); }
-    V* try_get_2(StrName key) { return is_small() ?_small.try_get_2(key) : _large.try_get_2(key); }
-    bool del(StrName key){ return is_small() ?_small.del(key) : _large.del(key); }
-
-    V try_get_likely_found(StrName key) const { return is_small() ?_small.try_get(key) : _large.try_get_likely_found(key); }
-    V* try_get_2_likely_found(StrName key) { return is_small() ?_small.try_get_2(key) : _large.try_get_2_likely_found(key); }
-
-    bool contains(StrName key) const { return try_get(key) != default_invalid_value<V>(); }
-
-    V operator[](StrName key) const {
-        V val = try_get_likely_found(key);
-        if(val == default_invalid_value<V>()){
-            throw std::runtime_error(_S("NameDict key not found: ", key.escape()).str());
-        }
-        return val;
-    }
-
-    void clear(){
-        if(is_small()) _small.clear();
-        else _large.clear();
-    }
-
-    template<typename Func>
-    void apply(Func func) const {
-        if(is_small()) _small.apply(func);
-        else _large.apply(func);
-    }
-
-    pod_vector<StrName> keys() const{
-        pod_vector<StrName> v;
-        apply([&](StrName key, V val){
-            v.push_back(key);
-        });
-        return v;
-    }
-
-    pod_vector<NameDictItem<V>> items() const{
-        pod_vector<NameDictItem<V>> v;
-        apply([&](StrName key, V val){
-            v.push_back(NameDictItem<V>{key, val});
-        });
-        return v;
-    }
-
-    ~NameDictImpl(){
-        if(!is_small()) _large.~LargeNameDict<V>();
-    }
-};
 
 using NameDict = NameDictImpl<PyVar>;
 using NameDict_ = std::shared_ptr<NameDict>;
diff --git a/include/pocketpy/vm.h b/include/pocketpy/vm.h
index a08933fa..d87ac92b 100644
--- a/include/pocketpy/vm.h
+++ b/include/pocketpy/vm.h
@@ -488,11 +488,11 @@ public:
     void __unpack_as_list(ArgsView args, List& list);
     void __unpack_as_dict(ArgsView args, Dict& dict);
     [[noreturn]] void __raise_exc(bool re_raise=false);
-    void __init_builtin_types();
-    void __post_init_builtin_types();
     [[noreturn]] void __builtin_error(StrName type);
     [[noreturn]] void __builtin_error(StrName type, PyVar arg);
     [[noreturn]] void __builtin_error(StrName type, const Str& msg);
+    void __init_builtin_types();
+    void __post_init_builtin_types();
     void __push_varargs(){}
     void __push_varargs(PyVar _0){ PUSH(_0); }
     void __push_varargs(PyVar _0, PyVar _1){ PUSH(_0); PUSH(_1); }