Performance - before using a foreach loop check if the list is empty

Unless you need some specific logic if the list is empty, then the if statement is certainly redundant. In the foreach loop if there is no data - it simply does not perform the loop.

This is more or less of a concern for best practice rather than performance though. The impact is practically non-existent; however, I think its never a bad I idea to at least be aware of these type of things.