The Common Language Runtime team at Microsoft is full of very smart people.  We are lucky enough in MSDN Magazine to have them writing an in-depth column every month to provide insights into the core of managed code, to share best practices, to explain some of the more obscure functionalities, and to present personal tips and suggestions, straight from the team that develops the platform.  In the January 2006 issue of the magazine, Kit George, now on the Visual Basic team, wrote a very useful edition of the column: CLR Inside Out: Base Class Library Performance Tips and Tricks.  In it, he discusses string concatenation, parsing, collections, reading from files, and a whole lot more.  If you haven't read it yet, I urge you to do so.  And if you have read it, go back and read it again... you may learn something new ;)

It's a lot of fun looking at the comments on this article that people have provided on the MSDN Magazine site (yes, we do look at the comments you submit).  This article has been very well received (and for good reason):

"Very insightful tips and will certainly help in my own development efforts."

"Phenominal information that is hard to find definitive evidence on. I appreciate it."

"important to once and for all state which is the best to do diffrnent things"

"Excellent tips on how to ensure the best performance on critial apps."

"Very useful ! Keep going, don't stop..."

"Good, clear explainations, nice simple examples."

"Tips and Tricks make my day more productive"

"Excellent, keep them coming"

"Good tipps if you want to tweak performance, learned of a lot of new functions..."

"I certainly won't use all of the mentioned considerations, but some are nice and clear some of my suspicions."

"It's always hard to list simple performance tricks that are of practical value. Several do not have any loss of functionality."

"Really a highly informative Content"

"Great! The type of in-depth bits that I want to read, and to be honest, get's me excited about the BCL/.NET"

"Very succinct and practical."

"I learnt a lot - in a quick way."