Which is faster foreach or linq

Count ; numbers. WriteLine "Doing warmup Start ; methodToTime ; stopwatch. Stop ; return stopwatch. Community Bot 1 1 1 silver badge. The question "is LINQ faster than a foreach" is wrong. You cannot compare both, a foreach can execute a LINQ query.

Moreover, both code snippets don't really do the same thing, as stated in Bradley's answer. The question is really "if I copy collection to list it is twice as slow if I don't, why doing twice as much work is twice slower" You can use foreach just fine in both cases to get exactly the same results.

Your code is comparing apples to oranges. If I write a LINQ expression that takes the first item from a list, it'll be faster than a foreach loop running a complex iteration and checks on all items of a list. A well-written foreach loop has less overhead than a LINQ query but a LINQ query may be easier to put together than a well-written, efficient foreach loop.

Some other perspectives to try would be to call. Show 6 more comments. Active Oldest Votes. LINQ will usually be faster when it can take advantage of deferred execution; as it does here. Thats the difference here. LINQ only enumerates once. I would be happy to use different wording if you have a suggestion. Either you forgot to clearly specify context OR your trying to confuse people I hope first The opening is better and I won't raise a fuss about it after changing "always"; the remainder of the answer is the meat and potatoes.

There are some subtleties with re-enumerating Enumerables and different query providers as well which sometimes comes up, which was the underlying motivation of my initial comment. AlexeiLevenkov Sorry, it was doing that in his code. That is not true of foreach in general of course.

You could add: use a foreach if you want to enumerate your LINQ query. So the foreach consumes it, both play well together since they have different purposes. Show 2 more comments. And yes, Linq uses iterators as well. Hans Passant Hans Passant k gold badges silver badges bronze badges.

That's not really meaningful though. Connect and share knowledge within a single location that is structured and easy to search. I am writing a Mesh Rendering manager and thought it would be a good idea to group all of the meshes which use the same shader and then render these while I'm in that shader pass. I am currently using a foreach loop, but wondered if utilising LINQ might give me a performance increase?

Most of the times, LINQ will be a bit slower because it introduces overhead. Do not use LINQ if you care much about performance. Use LINQ because you want shorter better readable and maintainable code.

LINQ-to-Objects generally is going to add some marginal overheads multiple iterators, etc. It still has to do the loops, and has delegate invokes, and will generally have to do some extra dereferencing to get at captured variables etc. In most code this will be virtually undetectable, and more than afforded by the simpler to understand code.

Re PLINQ; parallelism may reduce the elapsed time, but the total CPU time will usually increase a little due to the overheads of thread management etc. LINQ is slower now, but it might get faster at some point. The good thing about LINQ is that you don't have to care about how it works. If a new method is thought up that's incredibly fast, the people at Microsoft can implement it without even telling you and your code would be a lot faster. It should probably be noted that the for loop is faster than the foreach.

So for the original post, if you are worried about performance on a critical component like a renderer, use a for loop. Reference: In. NET, which loop runs faster, 'for' or 'foreach'? You might get a performance boost if you use parallel LINQ for multi cores. I was interested in this question, so I did a test just now. NET Framework 4.

It looks like LINQ might be faster than for each loop. Here are the results I got:. Before testing with an object Employee I tried the same test with integers. LINQ was faster there as well. This is actually quite a complex question.

Linq makes certain things very easy to do, that if you implement them yourself, you might stumble over e. This particularly applies to PLinq, and especially to parallel aggregation as implemented by PLinq.

In general, for identical code, linq will be slower, because of the overhead of delegate invocation. If, however, you are processing a large array of data, and applying relatively simple calculations to the elements, you will get a huge performance increase if:. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow.

Learn more. Again difficult to know from IL because that depends on what assembler instructions the JIT is emitting there. For example, if the devirtualization is not happening, that is enough to account for the massive difference you are looking at there. I am the author of Light. GuardClauses , an assertion library for checking parameter values in production code.

I'm currently considering whether it's useful to boost the performance of collection assertions - of course, these assertions are implemented in a generic way like the methods above are. I'm not that good in reading assembler language - but I will check if I can get hold of the assembler instructions. I have been looking at the code of GuardClauses and many of the patterns used internally are definitely not 'free' in the general sense. There are many tricks you can use to achieve almost zero overhead if you are willing to trick the JIT into emitting the proper code.

I have much to learn about performance optimizations. Will close this issue for now. Can I come back to you if I have further questions? Sure, I do 8 hours of performance consulting for Open Source projects as community work for free every month. Some like to write blogs, I am more of a 'get my hands dirty' kind of guy The proper question here is not why foreach is slower than LINQ but rather why foreach is slower than for.

In the case of arrays foreach and for should generate similar code and thus similar timings. If the timings are so different then there's a good chance that the 2 versions aren't comparable. After fixing it, the for loop version is as slow as the foreach version:. If you change it to use the other overload then it will probably be slow as well.

You may need to use a custom comparer to actually not being able to devirtualize and be as slow as those 2. My guess is that it has something to do with the fact that LINQ uses less lines of code, so the compiler is able to process the request faster.

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