Is Linq Faster, Slower or the same?

Question

Is this:

Box boxToFind = AllBoxes.Where(box => box.BoxNumber == boxToMatchTo.BagNumber);
EDIT:

Box boxToFind = AllBoxes.FirstOrDefault(box => box.BoxNumber == boxToMatchTo.BagNumber);

Faster or slower than this:

Box boxToFind ;
foreach (Box box in AllBoxes)
{
    if (box.BoxNumber == boxToMatchTo.BoxNumber)
    {
        boxToFind = box;
    }
}

Both give me the result I am looking for (boxToFind). This is going to run on a mobile device that I need to be performance conscientious of.

Answer 1

It should be about the same, except that you need to call First (or, to match your code, Last), not Where.
Calling Where will give you a set of matching items (an IEnumerable<Box>); you only want one matching item.

In general, when using LINQ, you need to be aware of deferred execution. In your particular case, it's irrelevant, since you're getting a single item.

Answer 2

If micro-optimization is your thing, LINQ performs worse, this is just one article, there are a lot of other posts you can find.

Answer 3

The fastest is when you are using for loop. But the difference is so small that you are ignore it. It will only matter if you are building a real-time application but then for those applications maybe C# is not the best choice anyway!

Answer 4

The difference is not important unless you've identified that this particular loop as a performance bottleneck through profiling.

If profiling does find it to be a problem, then you'll want to look into alternate storage. Store the data in a dictionary which provides faster lookup than looping through an array.

Answer 5

Micro optimization will kill you.
First, finish the whole class, then, if you have performance problems, run a profiler and check for the hotspots of the application.
Make sure you're using the best algorithms you can, then turn to micro optimizations like this.

In case you already did and I'm just being an asshole:
Slow -> Fast
LINQ < foreach < for < unsafe for (The last option is not recommended).
Abstractions will make your code slower, 95% of the time.

Answer 6

If AllBoxes is an IQueryable, it can be faster than the loop, because the queryable could have an optimized implementation of the Where-operation (for example an indexed access).