[jongs]

Why would it make it slower?

[carbocation]

Instead of just inserting a record, it now has to do something else, too (update the index).

Try taking a look at http://kevin.vanzonneveld.net/techblog/article/improve_mysql... , which suggests some things you can try. This might be a question better suited for StackOverflow, by the way.

[jongs]

thanks