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.
{
    WalletBatch batch(m_storage.GetDatabase());
    for (const auto& entry : privkey_map) {
        const CKey& key = entry.second;
        CPubKey pubkey = key.GetPubKey();
        const CKeyID& id = entry.first;
        assert(key.VerifyPubKey(pubkey));
        
        if (HaveKey(id)) {
            WalletLogPrintf("Already have key with pubkey %s, skipping\n", HexStr(pubkey));
            continue;
        }
        mapKeyMetadata[id].nCreateTime = timestamp;
        
        if (!AddKeyPubKeyWithDB(batch, key, pubkey)) {
            return false;
        }
        UpdateTimeFirstKey(timestamp);
    }
    return true;
}
bool LegacyScriptPubKeyMan::ImportPubKeys(const std::vector<CKeyID>& ordered_pubkeys, const std::map<CKeyID, CPubKey>& pubkey_map, const std::map<CKeyID, std::pair<CPubKey, KeyOriginInfo>>& key_origins, const bool add_keypool, const bool internal, const int64_t timestamp)