I write first for readability and performance second. Not to say that performance isn't important (and of course I pay attention to O notation), but throwing a little more memory and CPU power at a web page is far cheaper and easier than spending developer time reading code.
Wrong
From the article:
> It also turned out that Foreach often walks through the array faster than For
1. `ForEach` is slower.
2. `foreach` is faster.
3. Linq is slower.