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.
const std::vector<unsigned char>& vchCryptedSecret,
                                const CKeyMetadata &keyMeta)
{
    if (!WriteKeyMetadata(keyMeta, vchPubKey, true)) {
        return false;
    }
    if (!WriteIC(std::make_pair(DBKeys::CRYPTED_KEY, vchPubKey), vchCryptedSecret, false)) {
        return false;
    }
    EraseIC(std::make_pair(DBKeys::KEY, vchPubKey));
    return true;
}
bool WalletBatch::WriteMasterKey(unsigned int nID, const CMasterKey& kMasterKey)
{
    return WriteIC(std::make_pair(DBKeys::MASTER_KEY, nID), kMasterKey, true);
}
bool WalletBatch::WriteCScript(const uint160& hash, const CScript& redeemScript)
{
    return WriteIC(std::make_pair(DBKeys::CSCRIPT, hash), redeemScript, false);
}
bool WalletBatch::WriteWatchOnly(const CScript &dest, const CKeyMetadata& keyMeta)