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.
{
    return MakeUnique<LegacySigningProvider>(*this);
}
bool LegacyScriptPubKeyMan::CanProvide(const CScript& script, SignatureData& sigdata)
{
    IsMineResult ismine = IsMineInner(*this, script, IsMineSigVersion::TOP,  false);
    if (ismine == IsMineResult::SPENDABLE || ismine == IsMineResult::WATCH_ONLY) {
        
        
        
        return true;
    } else {
        
        ProduceSignature(*this, DUMMY_SIGNATURE_CREATOR, script, sigdata);
        if (!sigdata.signatures.empty()) {
            
            bool has_privkeys = false;
            for (const auto& key_sig_pair : sigdata.signatures) {
                has_privkeys |= HaveKey(key_sig_pair.first);
            }
            return has_privkeys;
        }
        return false;
    }
}
bool LegacyScriptPubKeyMan::SignTransaction(CMutableTransaction& tx, const std::map<COutPoint, Coin>& coins, int sighash, std::map<int, std::string>& input_errors) const