Are Linq's Skip and Take optimized for arrays? [4.0 edition]

Question

It's a common situation to copy a range from an array. C# supports this operation in various ways, for instance using Array.Copy, but also by Linq's Skip and Take combination.

Starting at .NET 4.0, do the Skip and Take operations still add considerable overhead, or do they recognize (either at compile time or at run time) their target is an array?

To clarify: I am referring to a) the time taken to skip the initial bytes and b) to the combination of Skip-Take-ToArray, which does not suffer from side effects. For instance, new byte[10000].Skip(9999).Take(1).ToArray() could be optimized this way and would (for large n) be noticeably faster.

Answer 1

Skip/Take still operate in O(n) due to how LINQ has to maintain knowledge of how elements even in arrays can be changed and how the objects have to stay aware of the changes.Therefore, while the optimizations to O(1) seems trivial, it is not currently realized.

See: https://edulinq.googlecode.com/hg/posts/40-Optimization.html

Jon Skeet had an excellent blog a few years back discussing these and more in "reimplementing LINQ" (http://codeblog.jonskeet.uk/2011/01/02/reimplementing-linq-to-objects-part-23-take-skip-takewhile-skipwhile/). It's a great read.