[wp-hackers] .htaccess cleanup

[Owen Winkler]

Jonathan Leighton wrote:

>Well, I'm just assuming that saying (in code of course) "match any
>character" is faster than saying "match this phrase, or that phrase, or
>that phrase, or that phrase". But yeah, I wouldn't know either.
>  
>
Not so much.  Matching something specific with a regex is *always* 
faster than maching anything because when the regex engine hits the end 
of the string that it matches, it backs out of the match to find what's 
next.

Consider: .*a
Match that against this:
bbbbbbbbacccccc

This would first match the '.*' part against the entire string, and then 
backtrack one chracter at a time to find the 'a' that would come next.  
7 assertions on 'c's would fail before it found the match.  As you can 
imagine, '.*?a' is worse on 'bbbabbba'.  All of this is subject to 
optimization that might improve the performance of the regex, but 
speaking generally you shouldn't match against anything when you know in 
advance what set of things you want to match against.

Whether this general case can be applied to the regexes mentioned, I 
don't know, and whether an inefficient '.*' regex would be faster than 
multiple not-'.*' regexes I also can't say.  It's a tradeoff that you 
would need to measure, and I  really don't think my WordPress serving 
bottleneck is in the regex configuration.  If I was looking to optimize, 
I might start elsewhere first.

Owen