Imagine you're sitting on your front stoop, strumming your guitar, and Eric Clapton comes out of nowhere to give you some pointers.
That's about what happened to me today. Earlier this week, Jon Skeet (described by Scott Hanselman as "the world's greatest living programmer) noticed something I posted on the IANA Time Zone list, and asked me about the Inner Drive Time Zone library.
So I sent him the package.
And this afternoon, he sent me a benchmark that he wrote for it. Just like that.
Of course, the benchmark showed that my stuff was about 10% as fast as the Noda Time library, an open-source project he curates. So, having a couple of hours for "personal development time" available, I optimized it.
The specific details of the optimization are not that interesting, but I managed to more than double the library's performance by changing about ten lines of code. (It's now 20% as fast as Noda.) Along the way I exchanged about 10 emails with Skeet, because he kept making really crack suggestions and giving me valuable feedback about both my design and his.
That was cool.