Huge CPU usage difference for the same .NET 4 program on different machines

I have two servers, one running core i7 920 (8 logic CPUs at 2.8Ghz), the other running Xeon X3430 (4 logic CPUs at 2.开发者_如何学Python4Ghz). For the same .NET 4 application, CPU usage on the first machine is 6%; on the second machine it is 50%! I wonder what makes this huge difference. And how can I diagnose the cause of the issue?

Its not just CPU that matters, are you saturating IO? Is the faster machine so much faster that it is writing much more data that the CPU cannot keep up, whereas the slower machine is rattling along and so the CPU fully utilised.

Locking might also have a part to play, I know a simple test app I wrote a long time ago showed large performance differences between a single core and quad core systems. (the single core was a lot faster, I think .NET optimised away locks for it whereas the quad core suffered).

In short, unless there's a fair bit more information on the problem, no-one can give you anything other than guesses as to the cause.