[Zope] External Method = Slow; Shell Script = Fast

Hello, I've got an external method that does some pretty complicated stuff. Basically it takes two XML files - one defines constraints, the other variables - and the script finds a solution using the variables that satisfies the constraints. At the command line (or executed via an external method that calls a shell script) execution is 2 seconds. As an external method execution is 15-20 seconds with the same input. Can anyone offer tips or strategies to improve performance? It would be obnoxious to have to encode objects for passing to a shell script. --- Edward J. Pollard, B.Sc Webmaster, University of Lethbridge Ext. 1828