会话与SQL查询与缓存| 用户对象

In my System Im using an Object User to store all the needend UserData wich I get from the Database.

In the Session Im storing the User ID. On Page call I query the User Data from the DB and store it into the User-Object.

Now I saw somebody storing all the User-Object into the Session.

I wondered whats the better way?

I saw this Post here on SO, wich helped a bit.

But 2 Things:

1) To lower the risk of Session-Hijacking Im creating a new Session on every Page Load. Therefore all the Data from the Session Object gets transfered.

2) Somthere else I saq that PHP 5 has an Cache already in the Pack. So Does it automaticly store the User Object?

Thanks in advance for your replays!