In .Net, when if ever should I pass structs by reference for performance reasons?

Question

In my C# application, I have a large struct (176 bytes) that is passed potentially a hundred thousand times per second to a function. This function then simply takes a point

Answer 1

I did some very informal profiling, and the results indicate that, for my particular application, there is a modest performance gain for passing by reference. For by-value I got about 10,050,000 calls per second, whereas for by-reference I got about 11,200,000 calls per second.

Your mileage may vary.