我的代码中这一段循环太慢了，怎么可以提速啊
for uuid in range (batch_size):
user_id = user[uuid]
pos_id = pos_items[uuid]
posass_id = posass_items[uuid]
s_1 = s_tensor[user_id][pos_id]
s_2 = s_tesor[user_id][posass_id]
i_loss_1 = tf.where(s_1>s_2,a,b）
