Is it a bad practice to leave an entire Cache Model in IIS?

In an application I use several times a code like

var cliente = db.Clientes.Find(id);

So I created a controller that returns me:

[OutputCache(Duration = (10 * 60 * 60), VaryByParam = "id")]
    public static Cliente ClienteInfo(int id)
    {
        using (WMBContext db = new WMBContext())
        {
            return db.Clientes.Find(id);
        }
    }

It has been extremely fast, however I am writing the entire model cached, imagining that different ids will be around 300, so they will be 300 x Model in memory in IIS. I remember that it was not advisable to store whole RecordSets in Session, in theory I'm not doing this?

Now I do not know what's best, fetching 6000x in the database or storing 300model in memory.

Is there a way to check the memory used in the cache? will it be linked to the pool? (the code is not yet in production)

Edit OBS: This model has relationships with other models and has more than 30 properties.