think logically, we are doing the transaction by paying a fee, sometimes it is still often the case pending or slow finish, try to think if it doesn't pay,Bitcoin transactions are in place as an incentive to miners when validating bitcoin blocks. One of the reasons there is a fee is because the larger the transaction data size, the longer and more energy it will take miners to validate the data. Transactions with higher transaction fees tend to be validated faster in the blockchain. Conversely, transactions with low or zero transaction fees tend to be validated more slowly, or eventually will get rejected.