two questions regarding default audit behavior

[Bill Tangren]

I have two questions regarding default audit behavior (i.e. auditd is running, 
but there is nothing in audit.rules but "-D" and "-b 256"):

1) what is being audited?

2) can I use the -D command to prevent those things from being audited?

I am required to have auditing running, but what I need to audit is specific. 
One server in particular is slow (a 750 MHz Pentium III) to start with, and 
default auditing is slowing it down to a crawl.

Bill Tangren