在页面中运行查询加载一个坏主意？

I'm running an ASP.NET app in which I have added an insert/update query to the [global] Page_Load. So, each time the user hits any page on the site, it updates the database with their activity (session ID, time, page they hit). I haven't implemented it yet, but this was the only suggestion given to me as to how to keep track of how many people are currently on my site. I'm running an ASP.NET app in which I have adde