What is the fastest way to copy my array?

Question

I'm doing some Wave file handling and have them read from disk into an array of bytes. I want to quickly copy portions from this byte array into another buffer for intermediate processing. Currently I use something like this:

float[] fin;
byte[] buf;
//fill buf code omitted
for(int i=offset; i < size; i++){
  fin[i-offset] = (float) buf[i];  
} 

I feel that this is a slow method, because there is as much computation going on in the for loop conditional and increment as there is over in the actual body. If there was a block copy avaliable in C# or some other way I can implement a block copy, that would be great.

Maybe it isn't too slow, but it sure looks like a lot of work to move some data over. Here "size" is between 2^10 and 2^14. I am then handing the "fin" off to a FFT library, so this is by no means the slowest part of the code, maybe I'm barking up the wrong tree.

EDIT UPDATE: I realize that micro optimizations are not where someone should spend their time, and I realize that profiling is a better way to achieve speedups overall, but I know that this code is in a 'hot path' and must be completed in under a third of a second on varying end user architectures to minimize our hardware system requirements. Even though I know that the following FFT code will be much more time consuming, I am looking for speedups where I can get them.

Array.Copy sure looks nice, I didn't know about that before, and I consider this Q&A a success already!

Answer 1

There is also:

Array.Copy
Array.CopyTo

but whether these will be faster will require profiling.

But be warned about focusing on micro-optimisations to the extent you miss the big picture, on modern PCs the effect of multi-level memory caching is likely to be greater than one approach or another to the copy.

Edit: Quick check in reflector: both of the above methods boil down to a common native implementation (good).

Note the docs for Array.Copy cover valid type conversions, a value -> value widening conversion like byte to float should be OK.