For a program I am writing I need to calculate the distances between coordinates. Seeing as I need to perform a large number of these calculations for each coordinate (thousands) it makes sense to convert to UTM, then calculate the distance (seeing as I am just comparing distances, I can even work with the square of the distance between the points).
At what point does this trade off make sense? As far as I can tell by reading the relevant calculations Greater Circle would be the faster algorithm, but obviously once you do the conversion to UTM you don't need to do it again. How many times do you need to run the Greater Circle algorithm before it makes sense to convert to UTM instead? (Assume that the accuracy isn't a big deal in my situation).