Ilya Chumakov has some tips for making Entity Framework inserts and updates a lot faster:
When adding or modifying a large number of records (10³ and more), the Entity Framework performance is far from perfect. The reasons are architectural peculiarities of the framework, and non-optimality of the generated SQL. Leaping ahead, I can reveal that saving data through a bypass of the context significantly minimizes the execution time.
There’s some good advice in here, though not my favorite advice, which is don’t use Entity Framework.