The session used in Login-Engine & autologin


The Login-Engine uses session to store the user information,if there is
a situation that high concurrent invitation that occurs in that
website,will session be a heavy load?
btw,is there any reference of implementing autologin using cookies?I
found one in,but it uses
session while not cookie, use cookie to enable autologin,i
think it will not give the burden to website,any references?thanks