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);
    
    
    
    CHDChain newHdChain;
    newHdChain.nVersion = m_storage.CanSupportFeature(FEATURE_HD_SPLIT) ? CHDChain::VERSION_HD_CHAIN_SPLIT : CHDChain::VERSION_HD_BASE;
    newHdChain.seed_id = seed.GetID();
    SetHDChain(newHdChain, false);
    NotifyCanGetAddressesChanged();
    WalletBatch batch(m_storage.GetDatabase());
    m_storage.UnsetBlankWalletFlag(batch);
}
/**
 * Mark old keypool keys as used,
 * and generate all new keys
 */
bool LegacyScriptPubKeyMan::NewKeyPool()