When running walletpassphrase on a large wallet.dat (ie about 300,000 segwit P2SH addresses) the command sometimes takes a very long time, and if command is run multiple times at once (while running slow) it causes bitcoin core to freeze (stops syncing and requires kill -9 to stop/restart)

During the locked up walletpassphrase commands being run the following messages start to appear in the debug.log:

`018-01-24 01:01:04 socket sending timeout: 1201s`

Note that this problem is intermittent, so sometimes the command runs instantly, other times it takes a few minutes, and other times it completely freezes the node.
}
};
static bool
ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue,
             CWalletScanState &wss, std::string& strType, std::string& strErr) EXCLUSIVE_LOCKS_REQUIRED(pwallet->cs_wallet)
{
    try {
        
        
        
        ssKey >> strType;
        if (strType == DBKeys::NAME) {
            std::string strAddress;
            ssKey >> strAddress;
            std::string label;
            ssValue >> label;
            pwallet->m_address_book[DecodeDestination(strAddress)].SetLabel(label);
        } else if (strType == DBKeys::PURPOSE) {
            std::string strAddress;
            ssKey >> strAddress;