Using the XslCompiledTransform Class
The XslCompiledTransform class is the Microsoft .NET Framework XSLT processor. This class is used to compile style sheets and execute XSLT transformations.
Although the overall performance of the XslCompiledTransform class is better than the XslTransform class, the Load method of the XslCompiledTransform class might perform more slowly than the Load method of the XslTransform class the first time it is called on a transformation. This is because the XSLT file must be compiled before it is loaded. For more information, see the following blog post: XslCompiledTransform Slower than XslTransform?