You are not specifying how are you doing the comparison, but here is my 2 cents:
Import the foxpro tables into the MySQL database and then you'll be able to do your update in a single SQL statement, which, even for that many records would take some only a few seconds, then delete th imported data. Importing the foxpro tables into MySQL will take a little longer but I'm sure that, once automated, the whole process shouldn't take more than a couple of minutes. HTH -- https://mail.python.org/mailman/listinfo/python-list
