I came across a great document about .net performance.

Essential Performance Facts and .NET Framework Tips is written by Bill C., who was a PM on Roslyn Team.

In 14 pages, you’ve got basic .net performances core issues (ie. they applies to any .net app, from mobile to datacenter), and span across different themes, notably allocations in:

• boxing,
• strings manipulation,
• async code,
• LINQ and lambdas.

PS.: If you like this kind of challenge, we’re hiring ;) DM me on twitter at @cmaneu.