Simply put, ReSharper is a must-have productivity tool for .NET developers. It fully integrates with Microsoft Visual Studio to intelligently and powerfully extend the functionality that is native to Visual Studio. ReSharper provides solution-wide error highlighting on the fly, instant solutions for found errors, over 30 advanced code refactorings, superior unit testing tools, handy navigation and search features, single-click code formatting and cleanup, automatic code generation and templates, and a lot more productivity features for C#, VB.NET, ASP.NET, XML, and XAML.
ReSharper 4.5 introduces the greatest performance boost in recent product history. Both performance and memory usage have been revamped. Several major actions such as solution opening, code editing and search and navigation are now performed 30–60% faster than before.