What is the efficiency and performance of LINQ and Lambda expressions in .Net?

Question

I have been using .Net 3.5 and VS 2008 for more than a month. Like most .Net developers, I developed from many years of experience in .NET 1.0 and 2.0 and VS 2005. I recently discovered the simplicity and power of LINQ and Lambda Expressions, as in my last questions, such as Find an item in a list by LINQ , Convert or map a class instance to a list of another using Lambda or LINQ and Convert or map the class list to another class list using Lambda or LINQ .

I admit that Lambda and LINQ are much simpler and easier to read, and they seem very powerful. Behind the scenes, the .Net compiler needs to generate a lot of code to achieve these functions. Therefore, I hesitate to switch to the new syntax a bit, since I already know the "old" way to achieve the same results.

My question is about the efficiency and performance of Lambda and LINQ. Maybe lambda expressions are basically built-in functions, in which case I think Lambda should be ok. How about LINQ?

Limit the discussion of LINQ-to-SQL LINQ-to-SQL (LINQ-to-SQL). Any comments, comparisons and experiences?

Answer 1

There is not a single answer that will be enough.

LINQ has many uses and many implementations, and therefore many implications for the effectiveness of your code.

As with every technology at your fingertips, LINQ can and will abuse and abuse the same way, and the ability to distinguish between this and the right use depends on only one thing: knowledge.

Therefore, the best advice I can give you is to familiarize yourself with how LINQ is really implemented.

Things you should check out:

• LINQ and methods for using extension methods and methods for existing collection types
  • How LINQ Works
  • How LINQ works inside (stack overflow)
  • How does encoding with LINQ work? What is going on behind the scenes?
• How LINQ-to-objects and LINQ-to-SQL differ
  • What is the difference between LINQ query expressions and extension methods (stack overflow)
• Alternatives to the new LINQ syntax, such as using the .Where (...) extension method for collections

And as always, when considering performance issues, the only safe approach is to simply measure. Create a code snippet using LINQ, which does one thing, knows something, and creates an alternative, then measures both. Guessing and assuming will only lead to poor results.

Answer 2

Technically, the fastest way is to control all the little things. Here are some performance tests . Note that the foreach keyword and the ForEach LINQ construct are identical much slower than just using and writing procedural code.

However, the compiler can and will be improved, and you can always profile your code and optimize any problem areas. It is generally recommended that you use more expressive features that make it easier to read code if you really don't need extra nanoseconds.

Answer 3

For LINQ queries with the “new syntax”, the generated IL (code) is essentially the same as calling the extension methods provided directly by Enumerable and Queryable.

Answer 4

Do not optimize prematurely. Use Linq and new extension methods if they improve readability and profile your application afterwards.

In most cases, the difference between Linq and using plain for loops is irrelevant at all. Improved maintainability of your code should cost several ms. Linq can be slower because it runs on meters that are implemented as state machines. So a simple (...) loop will be faster.

I would advise following the advice of Lasse V. Karlsens and adding http://www.davesquared.net/2009/07/enumerables-linq-and-speed.html to your list of links.

Answer 5

There is no performance difference between LINQ queries and Lambda expressions.

You must fully understand how the LINQ function (like Lambda, LINQ queries) works in .NET before you look at performance issues.

Basically, you can work with any of the LINQ and Lambda queries.

LINQ Queries

• This is a high level user readable request.

• It is converted to an equal Lambda expression and Lambda expressions added as nodes to the expression tree. An expression tree that makes the structure of lambda expressions. This is done by the compiler.

• The query provider scans the expressions (added as nodes in the expression tree) and creates uniform SQL queries, so an equal sql query is generated at runtime.

• Return type: result set (IEnumerable).

Lambda expressions

• This is a set of expressions / statements and creates a delegate / expression tree. It can be passed to the function as an argument.

• It supports all LINQ methods, such as LINQ queries. (Where, Select, Count, Sum, etc.)

• An expression tree has been created that makes the structure of the lambda expression. This is done by the compiler.

• The query provider scans the expressions (expression tree) and creates a uniform SQL query at runtime.

• Return Type: Delagate / Expression Tree

What's better?

You can understand LINQ (queries, lambda). If you look at the above points.

Advantage of LINQ Query - Readable.

Lambda Advantage

• Lambda will have an advantage, since it creates a delegate, and with delagte you can just go through enter parameters and get the result for different input parameters. You do not need to write different queries for different criteria as well.

• You can create a dynamic query using lambda expressions and expression trees.

• You can use Lambda expressions if you want to pass the result (s) to the method as an argument.

• expressions are shorter.

Therefore, a Lambda expression is best for developing on LINQ queries.

Answer 6

In some cases, LINQ is just as fast, if not faster than other methods, but in other cases it can be slower. We are working on a project that we converted to linq, and searching for data is faster, but merging data between the two tables is much slower. A bit of overhead, but in most cases I don’t see the difference in speed, which greatly affects your program.