diff --git a/AlphaGo/go.py b/AlphaGo/go.py
index 55f5a4a..987fe93 100644
--- a/AlphaGo/go.py
+++ b/AlphaGo/go.py
@@ -222,6 +222,10 @@ class Go:
             new_color = -color
             return [history_boards, new_color], 0
 
+    def simulate_hashable_conversion(self, state):
+        # since go is MDP, we only need the last board for hashing
+        return tuple(state[0][-1])
+
     def executor_do_move(self, history, latest_boards, current_board, color, vertex):
         if not self._rule_check(history, current_board, color, vertex):
             return False
diff --git a/AlphaGo/reversi.py b/AlphaGo/reversi.py
index c6c8a5b..08a5ec5 100644
--- a/AlphaGo/reversi.py
+++ b/AlphaGo/reversi.py
@@ -97,6 +97,10 @@ class Reversi:
         history_boards.append(new_board)
         return [history_boards, 0 - color], 0
 
+    def simulate_hashable_conversion(self, state):
+        # since go is MDP, we only need the last board for hashing
+        return tuple(state[0][-1])
+
     def _get_winner(self, board):
         black_num, white_num = self._number_of_black_and_white(board)
         black_win = black_num - white_num
diff --git a/tianshou/core/mcts/mcts.py b/tianshou/core/mcts/mcts.py
index 4c23809..9625261 100644
--- a/tianshou/core/mcts/mcts.py
+++ b/tianshou/core/mcts/mcts.py
@@ -1,17 +1,9 @@
 import numpy as np
 import math
 import time
-import sys
-import collections
 
 c_puct = 5
 
-def hashable_conversion(obj):
-    if isinstance(obj, collections.Hashable):
-        return obj
-    else:
-        return tuple(hashable_conversion(sub) for sub in obj)
-
 class MCTSNode(object):
     def __init__(self, parent, action, state, action_num, prior, inverse=False):
         self.parent = parent
@@ -109,7 +101,9 @@ class ActionNode(object):
         if self.next_state is None: # next_state is None means that self.parent.state is the terminate state
             self.mcts.action_selection_time += time.time() - head
             return self
-        self.next_state_hashable = hashable_conversion(self.next_state)
+        head = time.time()
+        self.next_state_hashable = simulator.simulate_hashable_conversion(self.next_state)
+        self.mcts.hash_time += time.time() - head
         if self.next_state_hashable in self.children.keys(): # next state has already visited before
             self.mcts.action_selection_time += time.time() - head
             return self.children[self.next_state_hashable].selection(simulator)
@@ -153,9 +147,7 @@ class MCTS(object):
         self.state_selection_time = 0
         self.simulate_sf_time = 0
         self.valid_mask_time = 0
-        self.ndarray2list_time = 0
-        self.list2tuple_time = 0
-        self.check = 0
+        self.hash_time = 0
 
     def search(self, max_step=None, max_time=None):
         step = 0
@@ -174,18 +166,16 @@ class MCTS(object):
             self.backpropagation_time += back_time
             step += 1
         if self.debug:
-            file = open("mcts_profiling.txt", "a")
+            file = open("mcts_profiling.log", "a")
             file.write("[" + str(self.role) + "]"
-                       + " sel  " + '%.3f' % self.selection_time + "  "
-                       + " sel_sta  " + '%.3f' % self.state_selection_time + "  "
-                       + " valid  " + '%.3f' % self.valid_mask_time + "  "
-                       + " sel_act  " + '%.3f' % self.action_selection_time + "  "
-                       + " array2list  " + '%.4f' % self.ndarray2list_time + "  "
-                       + " check " + str(self.check) + "  "
-                       + " list2tuple  " + '%.4f' % self.list2tuple_time + " \t"
-                       + " forward  " + '%.3f' % self.simulate_sf_time + "  "
-                       + " exp  " + '%.3f' % self.expansion_time + "  "
-                       + " bak  " + '%.3f' % self.backpropagation_time + "  "
+                       + " sel " + '%.3f' % self.selection_time + "  "
+                       + " sel_sta " + '%.3f' % self.state_selection_time + "  "
+                       + " valid " + '%.3f' % self.valid_mask_time + "  "
+                       + " sel_act " + '%.3f' % self.action_selection_time + "  "
+                       + " hash " + '%.3f' % self.hash_time + "  "
+                       + " step forward " + '%.3f' % self.simulate_sf_time + "  "
+                       + " expansion  " + '%.3f' % self.expansion_time + "  "
+                       + " backprop " + '%.3f' % self.backpropagation_time + "  "
                        + "\n")
             file.close()