Sitecore and GlassMapper - how much a GlassCast<> costs

We are using the GlassMapper on many projects, I just want to know how it affects performance.
I have about 20000 Items for testing (Articles) with about 20 fields, in first code I use the GlassCast to get Titles:

items.Select(item => item.GlassCast<Article>()).Select(art => art.Title).ToList();

In second part I will use the field directly:

items.Select(item => item[Article.TitleFieldName]).ToList();

In first case, when we use the GlassCast average time was 00:00:55.23 In second case average time was 00:00:00.034

It's almost 2000 times faster, so we should use it carefully!

Starting with Sitecore Analytics MongoDB API

I see a lot of questions about how to start using it, so this is a short post about.
For example let's get all Visits data for the last month (last 30 days) for our particular site. First of all we need to get the MongoDB collection named "Interactions" it has all Visits data:

//Connecting to the Analytics DB
var driver = Sitecore.Analytics.Data.DataAccess.MongoDb.MongoDbDriver.FromConnectionString("analytics");

//Building our query
var builder = new QueryBuilder();
var filter = builder.And(builder.GTE(_ => _.StartDateTime, DateTime.Now.AddDays(-30)), builder.EQ(_ => _.SiteName, siteName.ToLower())); 

//Retrieving data from the "Interactions" collection
var interactions = driver.Interactions.FindAs(filter)

In similar way you can get other data.

That is it!