Hi Frank,
2010/10/11 Frank Ralf Frank.Ralf@gmx.net:
Sounds like a caching related problem. See http://www.mediawiki.org/wiki/Manual:Cache for further information.
You might also have a look at http://www.mediawiki.org/wiki/Manual:Job_queue and http://www.mediawiki.org/wiki/Manual:$wgJobRunRate which regard to periodically run job in MediaWiki.
thanks for the hint. It seems as if APC in conjunction with PHP-mod_fastcgid was the culprit. Switched to eAccelerator today, let's see how that goes.
Florian