I had today a real problem with my php-fpm and nginx setup: The server was really slow, the 5 php workers took alot of RAM (about 1GB in total, while i only have 512MB RAM and 2GB SWAP) and produced a high load. I found out that this was probably caused by a gallery2 installation that was generating new thumbnails on about 200 Images. After i switched the gallery2 to use imagemagick (which uses the binaries from /usr/bin and not the php implementation of GD) and restartet the php-fpm everything was back to normal and even the thumbnail generation was very quick.
The Question is, why is GD so much slower and more RAM consuming than imagemagick? Is there any configuration fault? I never had this problem before (but the old server was much faster hardware...)
In the php.ini i cannot spot any configuration for GD at all, so it presumably runs in default config.