Read compressed XML file inside ZIP and parse data as fast as possible

Question

I am trying to read and parse an XML file inside of a ZIP archive as fast as possible. The XML file is roughly 85GB in size, so I know for a fact that I/O also plays a role here, as I need to essentially read 85GB total. However, reading 85GB on a 500 MB/s SSD, means I can do this in less than 3 minutes, if we ignore CPU, decompression, and so on.

As I cannot store the ZIP file nor XML file in memory, I've streamed the content, and it works really well. Reading and parsing 100.000 XML nodes/elements (which is roughly 450.000 lines of XML) takes about 10 seconds. Don't get me wrong: Reading 400.000+ lines of XML and parsing it in ~10 seconds is fast. But it's not as fast as I want.

Multi threading this is probably not an option, but I am interested in hearing, if it's possible to speed this up.

_models is just a List<Model> that I use to keep my objects in, which gets cleared once they're saved to the database.

public static async Task Main(string[] args)
{
    XmlReaderSettings settings = new XmlReaderSettings();
    settings.Async = true;

    using (var stream = new ZipInputStream(File.OpenRead($@"C:\file.zip")))
    {
        // this is fine, as we know there is only 1 file in the ZIP
        stream.GetNextEntry();

        using (XmlReader reader = XmlReader.Create(stream, settings))
        {
            reader.MoveToContent();

            while (await reader.ReadAsync())
            {
                if (reader.NodeType == XmlNodeType.Element)
                {
                    if (reader.Name == "ns:ElementName")
                    {
                        await ExtractModel(reader);
                    }
                }
            }
        }
    }

    // await save to database
}

private static async Task ExtractModel(XmlReader reader)
{
    XElement el = XNode.ReadFrom(reader) as XElement;

    var serializer = new XmlSerializer(typeof(Model));

    var model = (Model)serializer.Deserialize(el.CreateReader());

    _models.Add(model);

    // save 100.000 models to database
    if (_models.Count == 100000)
    {
        //await save to database
        _models.Clear();
    }
}
```