can I run Session class without Active Records ?

[eluser]Mahmoud M. Abdel-Fattah[/eluser]
I'm developing a web 2.0 website, which may have some million items, with some thousands users !!

Before starting using CI, I read a lot on this forum to know if CI is good for HUGE / BIG / LARGE projects, and I found that no problem with it. but in one post I found a reply that doesn't recommend using Active Records on big websites.

So, can I use SESSIONS class without ACTIVE RECORDS ? or should I use native php session functions ?!

If not, I want to make a $_SESSION check in the beg. of each file, So, what should I create (library / model) ?