NHibernate Hidden Gems - Speed up NHibernate startup time

This code is pulled directly from Ayende's presentation at NHDay in Bologna. I would just link there, but this code only exists in the video (no source was provided).

Here's a simple solution that Ayende showed to speed up the NHibernate startup time. The following will work great for production systems. You would need something a little more complex for development since you would need to re-save the cfg file anytime you change your mappings.

if (!File.Exists("nh.cfg"))
{
 // Build your nh configuration
 Configuration configuration = new Configuration()
   .Configure("NHibernate.config");
 // write the config out to a file (the configuration is expensive to create) 
 new BinaryFormatter().Serialize(File.Create("nh.cfg"), configuration);
}
var configuration = (Configuration)new BinaryFormatter().Deserialize(
 File.Open("nh.cfg", FileMode.Open)
);

ISessionFactory factory = configuration.BuildSessionFactory();