Why does C# execute Math.Sqrt() more slowly than VB.NET?

Question

Background

While running benchmark tests this morning, my colleagues and I discovered some strange things concerning performance of C# code vs. VB.NET code.

Answer 1

The difference is in the loop; your C# code is computing the square root on every iteration. Changing that one line from:

for (Int32 i = 2; i <= Math.Sqrt(suspectPrime); i++) {

to:

var lim = Math.Sqrt(suspectPrime);
for (Int32 i = 2; i <= lim; i++) {

dropped the time on my machine from 26 seconds to 7.something.