I have a function, which use EF, but it works too slow...
Do you know any ways, how to improve performance of this function?

```
public static void SaveCombiners()
    {
        using (var db = new IP_dbEntities())
        {
            db.COMBINERs.RemoveRange(db.COMBINERs);
            foreach (var type1 in EventTypesList)
            {
                foreach (var type2 in EventTypesList)
                {
                    db.COMBINERs.Add(new COMBINER()
                    {
                        EVENTS_TYPE = db.EVENTS_TYPE.Single(type => type.event_type == type1),
                        EVENTS_TYPE1 = db.EVENTS_TYPE.Single(type => type.event_type == type2),
                        combine_status = _eventTypesCombinerCollection[type1][type2].Value == true ? "+" : "-"
                    });
                }
            }
            db.SaveChanges();
        }
    }

```