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.
{
    LOCK(cs_KeyStore);
    UpdateTimeFirstKey(meta.nCreateTime);
    m_script_metadata[script_id] = meta;
}
bool LegacyScriptPubKeyMan::AddKeyPubKeyInner(const CKey& key, const CPubKey &pubkey)
{
    LOCK(cs_KeyStore);
    if (!m_storage.HasEncryptionKeys()) {
        return FillableSigningProvider::AddKeyPubKey(key, pubkey);
    }
    if (m_storage.IsLocked()) {
        return false;
    }
    std::vector<unsigned char> vchCryptedSecret;
    CKeyingMaterial vchSecret(key.begin(), key.end());
    if (!EncryptSecret(m_storage.GetEncryptionKey(), vchSecret, pubkey.GetHash(), vchCryptedSecret)) {
        return false;
    }
    if (!AddCryptedKey(pubkey, vchCryptedSecret)) {
        return false;
    }
    return true;
}
bool LegacyScriptPubKeyMan::LoadCryptedKey(const CPubKey &vchPubKey, const std::vector<unsigned char> &vchCryptedSecret)
{
    return AddCryptedKeyInner(vchPubKey, vchCryptedSecret);
}
bool LegacyScriptPubKeyMan::AddCryptedKeyInner(const CPubKey &vchPubKey, const std::vector<unsigned char> &vchCryptedSecret)