I need to use the src-dn of an object in an rule a couple of times.

What I am wondering, what is the relative cost/performance of using
XPATH for @src-dn each time, versus setting a local variable, and using
the LV each time?

I understand that for a single op, big deal, we are taking mili if not
microseconds, but it happens to be in one of my stupidly inefficient
rules (Query all ACL's in a tree, and start looking for people with too
many rights) so even minor savings over 10,000 instance nodes with many
value nodes can make a noticeable difference. (Yes I know, use a Hash
tree to make it faster, but lets keep this civilized please).

I have no idea how I would even test this?

I guess I could contrive a case to repeat something 10,000 times, using
@src-dn say 10 times inside the loop, then do it again using LV's and
compare total time over 100 runs (to eliminate other server processes
interferring, so average it out)...

Hmm, I could even output the results into an email and mail it to
myself... Right out time as start(In CTIME),finish (In CTIME) Hey,
anyone know if Google Docs lets you mail data into a form? I could send
it right into a Google Doc Spreadsheet and have the forumla to report
speed right there waiting for data...

That could be amusing... I might just try that...

More seriously though, Father Ramon, or Perrin, any thoughts? (Is
anyone else qualified to answer this question?)