bootstrap_access Phase

Hi,

I am a newbie currently crunching everything I can lay my hands on about Drupal. Please bear with me if my questions are a tad "green."

when I am learning from how drupal executes, I have noticed that the Bootstrap_access (phase 3) comes after the page cache, and the database abstraction layer.

My question is, is it necessary for the banned IP to go through these 2 phases - the page cache and the database abstraction layer phase? Once the global vars are initiated can't we just banned them right after phase 1?

or is there something that I am missing here? If I move the phase to execute earlier, even though the performance gain is very insignificant, (probably next to nothing, com'on, how may IPs am I banning here?) Will it cause negative impact or some unexpected behaviors?

Thank you!!