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.
case TX_WITNESS_V0_KEYHASH:
    {
        if (sigversion == IsMineSigVersion::WITNESS_V0) {
            
            return IsMineResult::INVALID;
        }
        if (sigversion == IsMineSigVersion::TOP && !keystore.HaveCScript(CScriptID(CScript() << OP_0 << vSolutions[0]))) {
            
            
            
            break;
        }
        ret = std::max(ret, IsMineInner(keystore, GetScriptForDestination(PKHash(uint160(vSolutions[0]))), IsMineSigVersion::WITNESS_V0));
        break;
    }
    case TX_PUBKEYHASH:
        keyID = CKeyID(uint160(vSolutions[0]));
        if (!PermitsUncompressed(sigversion)) {
            CPubKey pubkey;
            if (keystore.GetPubKey(keyID, pubkey) && !pubkey.IsCompressed()) {
                return IsMineResult::INVALID;
            }
        }
        if (keystore.HaveKey(keyID)) {
            ret = std::max(ret, IsMineResult::SPENDABLE);
        }
        break;
    case TX_SCRIPTHASH:
    {
        if (sigversion != IsMineSigVersion::TOP) {