Performance impact of auditing objects

I'm looking at the use of the audit journal to detect
changes in objects, esp. IFS. From looking at the
Security Reference, it seems I need to CHGAUD on all the
objects I want to monitor, and, for our purposes, that
means just about everything. I intend to exclude as much
as I can - things like /QIBM/ProdData/*, "include"
directories, remotes, symbolic links, etc.

I've been told that this approach is in use by some of
the high availability folk.

The manual does say that auditing EVERYthing can hurt
performance. But we're not doing everything, and only
changes, not use.

Since the check for whether to audit is done every time
an object is touched, anyway, right, the cost comes when
writing to the journal. And since this is for change
only, not use (read), is the hit acceptable?

Other issues raise their ugly heads - coexistence with
other products using the audit journal, management (for
our purposes we don't NEED a long audit trail), but
that's a whole 'nuther story.

Thanks

Vern