def __init__(self, save_file, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.changed = True
-        self.changed_fovs = True
+        self.changed_tiles = []
         self.io = GameIO(self, save_file)
         self.tasks = {}
         self.thing_types = {}
 
     def remove_thing(self, t):
         self.things.remove(t)
-        self.changed_fovs = True
+        self.record_fov_change(t.position)
 
     def add_thing(self, type_, position, id_=0):
         t_old = None
             self.things[self.things.index(t_old)] = t
         else:
             self.things += [t]
-        self.changed_fovs = True
+        self.record_fov_change(t.position)
         return t
 
     def send_gamestate(self, connection_id=None):
             player.prepare_multiprocessible_fov_stencil() #!
             player_fovs += [player._fov]
             player_fov_ids += [player.id_]
+            print('DEBUG regen FOV for', player.id_)
         if len(player_fovs) > 0:
-            print('DEBUG regenerating FOVs')
             pool = multiprocessing.Pool()
             new_fovs = pool.map(FovMap.init_terrain, [fov for fov in player_fovs])  #!
             pool.close()
                                                        quote(annotation)), c_id)
         self.io.send('GAME_STATE_COMPLETE')
 
+    def record_fov_change(self, position):
+        big_yx, little_yx = position
+        self.changed_tiles += [self.map_geometry.undouble_yxyx(big_yx,
+                                                               little_yx)]
+
     def run_tick(self):
         to_delete = []
         for connection_id in self.sessions:
                     for connection_id in [c_id for c_id in self.sessions
                                           if self.sessions[c_id]['thing_id'] == t.id_]:
                         self.io.send('PLAY_ERROR ' + quote(str(e)), connection_id)
-        if self.changed_fovs:
-            for t in [t for t in self.things if t.type_ == 'Player']:
-                t.invalidate_map_view()
         if self.changed:
             self.turn += 1
             # send_gamestate() can be rather expensive, due to among other reasons
-            # re-calculating each player's FOV, so don't send it out too often
+            # re-calculating players' FOVs, so don't send it out too often
             if self.last_send_gamestate < \
                datetime.datetime.now() -self.send_gamestate_interval:
+                if len(self.changed_tiles) > 0:
+                    for t in [t for t in self.things if t.type_ == 'Player']:
+                        fov_radius = 12  # TODO: un-hardcode
+                        absolute_position =\
+                            self.map_geometry.undouble_yxyx(t.position[0],
+                                                            t.position[1])
+                        y_range_start = absolute_position.y - fov_radius
+                        y_range_end = absolute_position.y + fov_radius
+                        x_range_start = absolute_position.x - fov_radius
+                        x_range_end = absolute_position.x + fov_radius
+                        for position in self.changed_tiles:
+                            if position.y < y_range_start\
+                               or position.y > y_range_end:
+                                continue
+                            if position.x < x_range_start\
+                               or position.x > x_range_end:
+                                continue
+                            t.invalidate_map_view()
+                            break
                 self.send_gamestate()
                 self.changed = False
-                self.changed_fovs = False
+                self.changed_tiles = []
                 self.save()
                 self.last_send_gamestate = datetime.datetime.now()
 
 
             raise PlayError('blocked by impassable tile')
 
     def do(self):
+        self.thing.game.record_fov_change(self.thing.position)
         self.thing.position = self.get_move_target()
+        self.thing.game.record_fov_change(self.thing.position)
         if self.thing.carrying:
             self.thing.carrying.position = self.thing.position
-        self.thing.game.changed_fovs = True
 
 
 
         big_yx = self.thing.position[0]
         little_yx = self.thing.position[1]
         self.thing.game.maps[big_yx][little_yx] = self.args[0]
-        self.thing.game.changed_fovs = True
+        self.thing.game.record_fov_change((big_yx, little_yx))
 
 
 
             if not self.thing.game.can_do_tile_with_pw(*yxyx, self.args[0]):
                 continue
             self.thing.game.maps[yxyx[0]][yxyx[1]] = '.'
-        self.thing.game.changed_fovs = True
+            self.thing.game.record_fov_change(yxyx)
 
 
 
                 t.open()
             else:
                 t.close()
-        self.thing.game.changed_fovs = True
+            self.thing.game.record_fov_change(t.position)
 
 
 
         self.thing.send_msg('RANDOM_COLORS')
         self.thing.send_msg('CHAT "You are drunk now."')
         self.thing.drunk = 10000
-        self.thing.game.changed_fovs = True
+        self.thing.invalidate_map_view()
 
 
 
         else:
             from plomrogue.misc import quote
             self.thing.game.hats[self.thing.name] = self.thing.carrying.design
-            self.thing.game.things.remove(self.thing.carrying)
+            self.thing.game.remove_thing(self.thing.carrying)
             self.thing.carrying = None
             self.thing.send_msg('CHAT "You put on a hat."')