Jan said that I have caching turned off, which surprised me because I thought it was on. Now I've looked at the code and I still think it is on.
wikiSettings.php: $useCachedPages = true ;
wikiLocalSettings.php: # $useCachedPages = false; # Disable page cache
(This is commented out, right?)
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Playing with benchmarking, grabbing a normal article 100 times:
(I know that this type of benchmarking is not very scientific, since conditions may change on the live server due to someone else doing something big at the same time, etc. But I think it gives an indication.)
As the site is running: /apache/bin/ab -n100 -c1 http://www.wikipedia.com/wiki/Alabama Requests per second: 0.95 [#/sec] (mean)
Now I will set $useCachedPages to false by uncommenting the line in wikiLocalSettings.php.
/apache/bin/ab -n100 -c1 http://www.wikipedia.com/wiki/Alabama Requests per second: 0.97 [#/sec] (mean)
So I see no material difference.
How can I easily tell if caching is actually on or off? Am I doing something wrong here?