Questions about SESSIONS

hi there,

hope you guys can help me out with this:

is there a lot of resource drain on the servers if I employ plenty of SESSION usage in my scripts?

i'm working on a restricted membership system thingy that requires users to login, and then have SESSION variables to track their movements and usage across the website.

how much does the usage of SESSIONS affect the server performance, if, let's say... a few hundred users are logged in at the same time, and each of them have several SESSION variables assigned to them?

or is it better to use COOKIES for this purpose? my only concern with cookies, is that a lot of users actually turn these things off in their browsers, and some browsers actually do not support cookies at all?


thanks.