Wondering if someone can clear this up for me.  Speed and optimization is a factor for me on a project I am working on and I was wondering if there are any performance differences between the following when loading content.

In this particular case there are many portions of the site where I need to 'refresh' content after some action has occurred.  Say, for example, on click of a button I want to show a table of information which is generated with php... the values will change so I am 'refreshing' the table on click.  Should I load the table html/php from an external file, reload it from within the page itself, etc?

Logic tells me loading an external file would be best, but I have not found any information about this.  Thanks for any information!

index.php (loading external page)

1. $myElem = $('#content'); //performance for not checking dom
2. $myElem.load('example.php');

index.php (loading div within external page)

1. $myElem = $('#content'); //performance for not checking dom
2. $myElem.load('example.php #somediv');

and last loading from within the page itself

index.php (loading external page)

1. $myElem = $('#content'); //performance for not checking dom
2. $myElem.load('index.php #somediv');