Track each logged in visitor on a profile page

I'm running an irc users page where people can register for an account and browse other users and leave them a comment, look at their pictures, vote for them and so on.

About a month ago I wrote a script that logged each user's visitors by writing the visitors nick, gender and age to a new table row. That way I could easily retrieve each user's ten latest visitors and output them on his page, so that the user could see which people last visited his page.

The problem is that this script apparently requires a lot of resources. On every visit a new row has to be written, and ten rows has to be retrieved. I'm running the page on a dedicated server which should be capable of handling quite a large amount of load, but this script still soaks too much resources, especially when there are a lot of users logged in.

I played a bit around with the script, but the only optimization I could think of was to writeonly the visiting user's ID to the table, and get his nick, gender and age in the retrieving process. I don't think this will be an optimization at all!

I've also though about using text files for logging, but would opening, writing and closing a text file every second really be a better way of doing this?

As you can see, I am in search of a script that can do what I'm trying to do above by using a minimum of resources. It does not have to be php or mysql based, the only requirement is that each user's visitors easily can be retrieved.

The server is a linux server running debian with apache.Start Free Trial