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.
if (sigversion == IsMineSigVersion::TOP) {
            break;
        }
        
        
        
        
        
        std::vector<valtype> keys(vSolutions.begin()+1, vSolutions.begin()+vSolutions.size()-1);
        if (!PermitsUncompressed(sigversion)) {
            for (size_t i = 0; i < keys.size(); i++) {
                if (keys[i].size() != 33) {
                    return IsMineResult::INVALID;
                }
            }
        }
        if (HaveKeys(keys, keystore)) {
            ret = std::max(ret, IsMineResult::SPENDABLE);
        }
        break;
    }
    }
    if (ret == IsMineResult::NO && keystore.HaveWatchOnly(scriptPubKey)) {
        ret = std::max(ret, IsMineResult::WATCH_ONLY);
    }
    return ret;
}
} 
isminetype LegacyScriptPubKeyMan::IsMine(const CScript& script) const