diff --git a/src/builtins.h b/src/builtins.h
index 690f85d8..98fb087e 100644
--- a/src/builtins.h
+++ b/src/builtins.h
@@ -210,7 +210,7 @@ list.__new__ = lambda obj: [i for i in obj]
 
 # https://github.com/python/cpython/blob/main/Objects/dictobject.c
 class dict:
-    def __init__(self, capacity=16):
+    def __init__(self, capacity=12):
         self._capacity = capacity
         self._a = [None] * self._capacity
         self._len = 0
@@ -243,7 +243,7 @@ class dict:
         else:
             self._a[i] = [key, value]
             self._len += 1
-            if self._len > self._capacity * 0.8:
+            if self._len > self._capacity * 0.67:
                 self._capacity *= 2
                 self.__rehash()
 
diff --git a/src/codeobject.h b/src/codeobject.h
index 1f7cc095..4a7bee34 100644
--- a/src/codeobject.h
+++ b/src/codeobject.h
@@ -64,8 +64,8 @@ struct CodeObject {
     std::map<StrName, int> global_names;
     std::vector<CodeBlock> blocks = { CodeBlock{NO_BLOCK, -1} };
     std::map<StrName, int> labels;
-    
-    int recommended_hashmap_capacity = 8;
+
+    int ideal_locals_capacity = 4;
 
     void optimize(VM* vm);
 
diff --git a/src/common.h b/src/common.h
index 7e37c9cf..76aa33ef 100644
--- a/src/common.h
+++ b/src/common.h
@@ -47,7 +47,9 @@ typedef int64_t i64;
 typedef double f64;
 #endif
 
-struct Dummy { char _; };
+struct Dummy {  };
+struct DummyInstance {  };
+struct DummyModule { };
 #define DUMMY_VAL Dummy()
 
 struct Type {
@@ -67,4 +69,6 @@ struct Type {
 
 #define RAW(T) std::remove_const_t<std::remove_reference_t<T>>
 
-const float kNameDictLoadFactor = 0.8;
\ No newline at end of file
+const float kLocalsLoadFactor = 0.8;
+const float kInstAttrLoadFactor = 0.67;
+const float kTypeAttrLoadFactor = 0.34;
\ No newline at end of file
diff --git a/src/namedict.h b/src/namedict.h
index 4eebad21..58cf3572 100644
--- a/src/namedict.h
+++ b/src/namedict.h
@@ -11,9 +11,11 @@ struct NameDictNode{
 struct NameDict {
     int _capacity;
     int _size;
+    float _load_factor;
     NameDictNode* _a;
 
-    NameDict(int capacity=2): _capacity(capacity), _size(0) {
+    NameDict(int capacity=4, float load_factor=0.67):
+        _capacity(capacity), _size(0), _load_factor(load_factor) {
         _a = new NameDictNode[_capacity];
     }
 
@@ -38,12 +40,13 @@ struct NameDict {
 
     int size() const { return _size; }
 
+//https://github.com/python/cpython/blob/main/Objects/dictobject.c#L175
 #define HASH_PROBE(key, ok, i) \
     int i = (key).index % _capacity; \
     bool ok = false; \
     while(!_a[i].empty()) { \
         if(_a[i].first == (key)) { ok = true; break; } \
-        i = (i + 1) % _capacity; \
+        i = (5*i + 1) % _capacity; \
     }
 
 #define HASH_PROBE_OVERRIDE(key, ok, i) \
@@ -51,7 +54,7 @@ struct NameDict {
     ok = false; \
     while(!_a[i].empty()) { \
         if(_a[i].first == (key)) { ok = true; break; } \
-        i = (i + 1) % _capacity; \
+        i = (5*i + 1) % _capacity; \
     }
 
     const PyVar& operator[](StrName key) const {
@@ -65,15 +68,15 @@ struct NameDict {
         if(!ok) {
             _a[i].first = key;
             _size++;
-            if(_size > _capacity * kNameDictLoadFactor){
-                __rehash_2x();
+            if(_size > _capacity * _load_factor){
+                _rehash_2x();
                 HASH_PROBE_OVERRIDE(key, ok, i);
             }
         }
         return _a[i].second;
     }
 
-    void __rehash_2x(){
+    void _rehash_2x(){
         NameDictNode* old_a = _a;
         int old_capacity = _capacity;
         _capacity *= 2;
@@ -122,8 +125,8 @@ struct NameDict {
         if(!ok) {
             _a[i].first = key;
             _size++;
-            if(_size > _capacity * kNameDictLoadFactor){
-                __rehash_2x();
+            if(_size > _capacity * _load_factor){
+                _rehash_2x();
                 HASH_PROBE_OVERRIDE(key, ok, i);
             }
         }
@@ -151,4 +154,7 @@ struct NameDict {
 
     inline iterator begin() const { return iterator(this, 0); }
     inline iterator end() const { return iterator(this, _capacity); }
+
+#undef HASH_PROBE
+#undef HASH_PROBE_OVERRIDE
 };
\ No newline at end of file
diff --git a/src/obj.h b/src/obj.h
index 1c0d75f5..fec434dd 100644
--- a/src/obj.h
+++ b/src/obj.h
@@ -25,7 +25,7 @@ struct Function {
     CodeObject_ code;
     std::vector<StrName> args;
     StrName starred_arg;                // empty if no *arg
-    pkpy::NameDict kwargs;          // empty if no k=v
+    pkpy::NameDict kwargs;              // empty if no k=v
     std::vector<StrName> kwargs_order;
 
     // runtime settings
@@ -97,8 +97,10 @@ struct Py_ : PyObject {
     Py_(Type type, T&& val): PyObject(type), _value(std::move(val)) { _init(); }
 
     inline void _init() noexcept {
-        if constexpr (std::is_same_v<T, Dummy> || std::is_same_v<T, Type>) {
-            _attr = new pkpy::NameDict();
+        if constexpr (std::is_same_v<T, Type> || std::is_same_v<T, DummyModule>) {
+            _attr = new pkpy::NameDict(8, kTypeAttrLoadFactor);
+        }else if constexpr(std::is_same_v<T, DummyInstance>){
+            _attr = new pkpy::NameDict(4, kInstAttrLoadFactor);
         }else{
             _attr = nullptr;
         }
diff --git a/src/pocketpy.h b/src/pocketpy.h
index 409cc7eb..7a11341d 100644
--- a/src/pocketpy.h
+++ b/src/pocketpy.h
@@ -774,6 +774,22 @@ void add_module_random(VM* vm){
     vm->_exec(code, mod);
 }
 
+void VM::post_init(){
+    init_builtins(this);
+    add_module_sys(this);
+    add_module_time(this);
+    add_module_json(this);
+    add_module_math(this);
+    add_module_re(this);
+    add_module_dis(this);
+    add_module_random(this);
+    add_module_io(this);
+    add_module_os(this);
+
+    CodeObject_ code = compile(kBuiltinsCode, "<builtins>", EXEC_MODE);
+    this->_exec(code, this->builtins);
+}
+
 
 class _PkExported{
 public:
@@ -879,21 +895,7 @@ extern "C" {
     __EXPORT
     /// Create a virtual machine.
     VM* pkpy_new_vm(bool use_stdio){
-        VM* vm = PKPY_ALLOCATE(VM, use_stdio);
-        init_builtins(vm);
-        add_module_sys(vm);
-        add_module_time(vm);
-        add_module_json(vm);
-        add_module_math(vm);
-        add_module_re(vm);
-        add_module_dis(vm);
-        add_module_random(vm);
-        add_module_io(vm);
-        add_module_os(vm);
-
-        CodeObject_ code = vm->compile(kBuiltinsCode, "<builtins>", EXEC_MODE);
-        vm->_exec(code, vm->builtins);
-        return vm;
+        return PKPY_ALLOCATE(VM, use_stdio);
     }
 
     __EXPORT
diff --git a/src/vm.h b/src/vm.h
index 7adcfe17..cc10960f 100644
--- a/src/vm.h
+++ b/src/vm.h
@@ -131,7 +131,7 @@ public:
             if(new_f != nullptr){
                 obj = call(*new_f, args, kwargs, false);
             }else{
-                obj = new_object(_callable, DUMMY_VAL);
+                obj = new_object(_callable, DummyInstance());
                 PyVarOrNull init_f = getattr(obj, __init__, false);
                 if (init_f != nullptr) call(init_f, args, kwargs, false);
             }
@@ -151,7 +151,9 @@ public:
             return f(this, args);
         } else if(is_type(*callable, tp_function)){
             const pkpy::Function& fn = PyFunction_AS_C(*callable);
-            auto _locals = pkpy::make_shared<pkpy::NameDict>(fn.code->recommended_hashmap_capacity);
+            auto _locals = pkpy::make_shared<pkpy::NameDict>(
+                fn.code->ideal_locals_capacity, kLocalsLoadFactor
+            );
             pkpy::NameDict& locals = *_locals;
 
             int i = 0;
@@ -323,7 +325,7 @@ public:
     }
 
     PyVar new_module(StrName name) {
-        PyVar obj = new_object(tp_module, DUMMY_VAL);
+        PyVar obj = new_object(tp_module, DummyModule());
         setattr(obj, __name__, PyStr(name.str()));
         _modules[name] = obj;
         return obj;
@@ -635,8 +637,12 @@ public:
         for (auto& name : pb_types) {
             setattr(builtins, name, _types[name]);
         }
+
+        post_init();
     }
 
+    void post_init();
+
     i64 hash(const PyVar& obj){
         if (is_type(obj, tp_str)) return PyStr_AS_C(obj).hash();
         if (is_int(obj)) return PyInt_AS_C(obj);
@@ -860,8 +866,9 @@ PyVar pkpy::NativeFunc::operator()(VM* vm, pkpy::Args& args) const{
 void CodeObject::optimize(VM* vm){
     int n = 0;
     for(auto& p: names) if(p.second == NAME_LOCAL) n++;
-    recommended_hashmap_capacity = (int)(n / kNameDictLoadFactor + 1.5);
-    if(recommended_hashmap_capacity < 2) recommended_hashmap_capacity = 2;
+    int base_n = (int)(n / kLocalsLoadFactor + 1.5);
+    ideal_locals_capacity = 2;
+    while(ideal_locals_capacity < base_n) ideal_locals_capacity *= 2;
 
     for(int i=1; i<codes.size(); i++){
         if(codes[i].op == OP_UNARY_NEGATIVE && codes[i-1].op == OP_LOAD_CONST){