Use of stored procedures and functions

[Ingvar Engelbrecht]

I have a PHP routine that is rather complex and it checks if one polygon shares any area with another polygon. One of the polygons is a bigger one with a fairly large number of coordinates so its a rather compute intense process. I am developing for a customer and he has suggested to change it to a MySQL stored procedure or function for better performance. After looking into this my opinion is that near to 200 lines of code and quite a lot of array processing I very much doubt that this is the way to go.
I would very much appreciate an opinion before delving into a complex conversion to a stored procedure or function. In my opinion the use of stored procedures is really what to use with complex queries not a lot of other processing but I might be wrong about that

If someone wants to check the code it is tempoarely displayed on my blog "Ingvar i Las Palmas" (ingvare.wordpress.com) "Code"