keyplyr - 8:11 pm on Nov 24, 2012 (gmt 0)
@ wilderness, the answer is once.
When you use a mod_rewrite to do the same task, each appearance of a nested condition starts the process back to the start of the line, so it may need to be read many times = greater load on server = greater processing time.
All this is theoretical, but if you have dozens of nested conditions (as I used to have before I switched) it could make a noticeable difference.
And yes, Jim was a big proponent of mod_rewrite, but later switched to mod_authz_host for blocking IP ranges. Somewhere there's a long discussion about this from a few years ago.