Adding BSON document to list is extremely slow

Question

for (int k = 1; k < list.Count(); k++)
        {
            List<BsonDocument> batch = new List<BsonDocument>();
            for (int i = 0; i < list[k].Count() - 1; i++)
            {
                var obj = new Dictionary<string, object>();
                obj.Add("Status", false);
                obj.Add("Headers", new BsonArray(list[0].ElementAt(0).ItemArray));
                List<string> formattedArray = new List<string>();
                for (int j = 0; j < list[k].ElementAt(i).ItemArray.Count(); j++)
                {
                    formattedArray.Add(JsonConvert.SerializeObject(list[k].ElementAt(i).ItemArray[j]));   
                }
                obj.Add("Values", new BsonArray(formattedArray.ToArray()));
                MongoDB.Bson.BsonDocument BSONDoc = new BsonDocument(obj);
                batch.Add(BSONDoc);
            }
            Insert(batch);
            batch.Clear();
        }

list.Count() = 121

list[k].Count() = 10000

list[k].ElementAt(i).ItemArray.Count() = 137

Answer 1

Here are couple of suggestions from me.

1) Assign list[k].Count() into a variable outside the loop.

2) new BsonArray(list[0].ElementAt(0).ItemArray). You can get this once and assign it to headers. No need to go for multiple times.

3) Finally, Run the Benchmark (using stopwatch) to see sections that are more time consuming.