(another, not entirely)sessions question

Hey there, I'm currently writing a web app using php. I was just looking for some advice on one aspect. On this site, users will be able to log in and post messages, or articles, or replies etc, you get the idea. Anyway, I am storing some info about the users, the usual stuff, name, email, password, all in mysql. I am also storing other info, such as when they last posted, and how many times they have posted. When a user posts a new message, the message is sent to mysql and stored in a table, at the same time, i also have to increment their total number of posts. The way this is done is by selecting the posts field on their userid, which i have to find using their username, which is set as a session var, when the user logs in. This all results in a good few queries to mysql. I was wondering would it be better to load all the user info, e.g. number of posts, last post date, into session vars, or should i set a cookie on the client side, or should i just continue with the queries. Any help is appreciated. conor