According to Donald Farmer who visited Slovenia a few months ago importing flat files
with SQL Server Integration Services is the fastest way today to do that.
SSIS now has a special very fast and very optimised library that transforms flat file text
into appropriate SQL Servers datatypes.
On very large files the speed gain is in the range of 7-20% of other ways.
More MSDN info here.
Now how do you get to that cute little option? here you go:
1. Run Visual Studio 2005
2. Under Business Inteligence Project create new Integration Services Project
3. Go to DataFlow tab
4. From Data flow Sources in the toolbox choose Flat File Source
5. Right mouse click on the component and choose Edit
6. Create new Flat file connection manager based on your flat file configuration.
7. Right mouse click on the component again and choose Show Advanced Editor
8. Go to tab Input and Output Properties tab
9. Expand Flat file source output and go to Output Columns
10. For each column set Fast Parse property to true
And there it is.
Enjoy the speed! :))
Performance testing compared to other bulk import methods is here.