Wouldn’t a quicker approach be to just make your path, then add a Debug statement that prints out the size of the path, and then revise your code after you’re done making the path and populate p.preallocateSpace() with the value from the Debug line? You can pull the size of the path from Path::toString() by parsing.
I posted a question about a similar thing regarding path sizes and how big do they have to be to start causing slowdowns.
