[VexXtreme]

Thank you for this awesome explanation, it really clarifies how Enumerable methods work. I guess this is the real reason behind deferred execution. Still, I can't help thinking there is a big overhead involved with using such methods. We did some benchmarks in the past and the code that does the same thing manually always ended up being much faster.

The nice thing about Enumerable methods is that they can significantly speed up development and most projects won't suffer for it. However, for speed critical code it's probably not the best tool in the box.