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);
    WalletBatch batch(m_storage.GetDatabase());
    return LegacyScriptPubKeyMan::AddKeyPubKeyWithDB(batch, secret, pubkey);
}
bool LegacyScriptPubKeyMan::AddKeyPubKeyWithDB(WalletBatch& batch, const CKey& secret, const CPubKey& pubkey)
{
    AssertLockHeld(cs_KeyStore);
    
    assert(!m_storage.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS));
    
    
    
    bool needsDB = !encrypted_batch;
    if (needsDB) {
        encrypted_batch = &batch;
    }
    if (!AddKeyPubKeyInner(secret, pubkey)) {
        if (needsDB) encrypted_batch = nullptr;
        return false;
    }
    if (needsDB) encrypted_batch = nullptr;
    
    CScript script;
    script = GetScriptForDestination(PKHash(pubkey));
    if (HaveWatchOnly(script)) {
        RemoveWatchOnly(script);
    }
    script = GetScriptForRawPubKey(pubkey);
    if (HaveWatchOnly(script)) {