I have a website that allows users to vote on content (up vote or down vote). Currently, every time a user accesses the index page, an SQL query is run to check whether the user has voted for a particular item (against a database with stored IP addresses). If the user has already voted, one of the two vote buttons is "greyed out" and if the user has not voted, both buttons are available to be clicked.

This query effects the site's performance during peak periods, so I would like to make the following change:

The code needs to be changed so that this query does not run on page load. Both vote buttons should always appear available to click. Only when a user clicks on a button will a "check if voted" query be run.

If the user clicks on an item they HAVE NOT yet voted for, their vote should be counted and the button they click should be greyed out for the remainder of their session.

If the user clicks on an item they HAVE already voted for, a message should appear reading "Already Voted", their vote will not be counted and the button will appear greyed out for the remainder of their session.

To accomplish this, I will assume you will need an advanced knowledge of both Ajax and SQL in addition to PHP and Javascript.