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An O/RM, like any layer of abstraction, introduces overhead to data access. In EF 5.0 we have taken steps to reduce this overhead and improve performance. As a result in one of our tests, repeat execution time of the same LINQ query has been reduced by around 6x. We also have an end-to-end application that we use for performance testing that is running 67% faster.
In EF 5.0 we are introducing automatic compilation of LINQ to Entities queries. From the first version of EF, developers have been able to compile LINQ queries explicitly by calling CompiledQuery.Compile, but many developers either were not aware of this ability or found the API harder to work with than regular LINQ. In EF 5.0 we took on some of this work for you, so that the translation of inline LINQ queries is now cached without having to use CompiledQuery. This improvement, together with an optimization in how we evaluate query parameter values, has had a profound impact on the query performance of EF:
The graph above represents the relative time spent in the execution of a query that retrieves an entity by its key. The same logical query was executed via ADO.NET, LINQ to SQL and several EF methodologies. In the benchmark, the query is executed in a loop using different key values each time. From the graph above we can see that before these performance improvements, executing a LINQ to Entities query for the second time took 23.14 times as long as the same SQL query using classic ADO.NET. With automatic query compilation and the changes to parameter evaluation, we’ve improved the performance of LINQ to Entities queries nearly 600% when compared against EF 4.0. As a bonus, EF 4.0 applications will get this performance improvement for free by just upgrading to .NET 4.5.
It would be amazing if we could give you 600% improved performance across the board. Unfortunately, most applications do more interesting things than run the same query repeatedly. Internally we have a suite of performance tests that run a variety of operations designed to simulate the typical usage a real-world application would have. We set thresholds based on the performance of EF 4.0 to ensure that we do not regress performance. These test runs are showing a 67% performance increase over EF 4.0 since we upgraded the server to EF 5.0:
This means that many real-world applications will automatically show substantially improved performance when they start using EF 5.0. Naturally, how much faster a specific application will become will depend on many variables that would be impossible to predict in a benchmark.
We aren’t done improving performance yet, but we’re excited about how much faster EF 5.0 is. These numbers are based on an internal build, but we’re working hard to get a build available for public verification of these improvements.
As always, your feedback is important to us. Feel free to leave comments or concerns below.
Thanks, The Entity Framework Team