We have a massive WinForms project with pretty serious performance issues:

1. Load times
2. LINQ-to-SQL (potential abuse of)
3. Etc.

If a mid/senior level developer on our team were to embark on a 3-6 month project to diagnose and potential tune the application, where would they start? Reading CLR for C# seems to be a good start, and maybe even using ReSharper's code analysis suite. Any papers, books, core CS topics to add to this toolkit would be helpful.