If you look at my first attempt block of code in the article you will notice multiple calculations with
... * Math.PI / 180.0
In my second attempt, I scoped some constants such as the "Math.PI / 180.0" to the user-defined function assembly (when the assembly is loaded into memory these values are available constants) by placing them in my class.
Public Const RadianConversionConst As Decimal = Math.PI / 180.0
The calculations in the function still have to perform some operations, but they don't have to perform as many operations with each call.
The result has 1 operation (other than dimensioning the variable) - 1 multiplication operation.
Dim Latitude1Radian As Decimal = Latitude1 * RadianConversionConst
Instead of of 2 operations - a multiplication operation and a divide operation.
Dim Latitude1Radian As SqlDecimal = Latitude1 * Math.PI / 180.0