I want to integrate an ORM with our system. Currently, we have a ton of tables, a ton of awful data, and stored processes. It's been said that employing an ORM can make the system slower. Does anyone know which ORM performs better when using queries made in C# code and mapping to stored procedures in terms of speed and performance?
The project will make use of huge, data-rich existing tables as well as stored procedures that run intricate activities in a SQL Server database. When running the current stored procedures and running queries against the current tables, the ORM must be able to execute transactions and have excellent performance. The project will employ WCF web services together with DDD and is web-based. I can see that EF is much simpler to use and offers more support, but is NH the best choice?