I have huge troubles running my cakephp application now.
after upgrading vom lenny to squeeze (even tried a complete reinstall of sqeeze) imagick is so incredible slow that it simply shuts down my server. I have several image galleries which use imagick to create thumbs.
50 images needed less then 30 seconds (2000x1200 pixel) on lenny. NOW it needs more than an hour.. Processor is at 100% for the complete time making other processes like apache very slow. is this a known bug in squeeze? it is making me crazy!
I even tried to run the application of other servers. a friend gave me access to his archlinux + nginx. fast as a rocket (less then 23 seconds). it is definitly a sqeeze problem.
i simply installed it via "apt-get install imagemagick" and added the php extension "php-imagick"
details: Version: ImageMagick 6.6.0-4 2010-11-16 Q16
One solution seems to be to downgrade imagemagick:
http://howto.at/2011/08/02/super-speed-up-virtuozzo-with-debian-6-and-imagemagick/
There's a debian bug (#638409) opened about this, seems to be caused by imagemagick's use of openmp:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=638409
Since we have this problem ourselves, we will be trying both solutions shortly :)