Batch Request in Https Post C#

Question

I have written C# Job to read from IIS line by line and create the JSON and post the data to DB.The Job is reading 45K lines and inserts operations are very slow. I enabled the parallel programming in job but still the performance was very slow. It took almost 2 Hours to complete the operation.

Here is my code snippet for calling the API:

              Parallel.For(0, logV.Count, counter =>
                    {

                        Console.WriteLine(JsonConvert.SerializeObject(logV[counter]));
                        var URL = WebConfigurationManager.AppSettings["URL"];
                        var client = new RestClient(URL);
                        var request = new RestRequest(Method.POST);
                        request.AddHeader("content-type", "application/json");
                        request.AddHeader("Authorization", "Basic TEST");
                        request.AddParameter("application/json", JsonConvert.SerializeObject(logV[counter]), ParameterType.RequestBody);
                        IRestResponse response = client.Execute(request);
                        Console.WriteLine("Lines read" + counter);
                    });

Here is my API:

   // POST: api/IISLogs
    public async Task<IHttpActionResult> Post(IISLog iislog)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        db.IISLogs.Add(iislog);
        await db.SaveChangesAsync();

        return CreatedAtRoute("DefaultApi", new { id = iislog.Id }, iislog);
    }

How can i do multiple inserts in Database using single HTTPS POST Opertaion or how can i convert the method as Batching?