What should we prefer for Omeka S in terms of performance : installing imagemagick commandline tools or imagemagick php wrapper imagick?
There shouldn’t be much difference in performance. The vast majority of the time spent doing thumbnailing will be the actual image processing and that’s going to be the same with the command-line ImageMagick and the extension Imagick.
For some servers one is available and one is not, or one is preinstalled and one is not, and that’s how I’d generally choose between them. On servers that restrict PHP from running command-line commands Imagick can be the only option, for example. If it’s a situation where both are equally available… I don’t think there’s really any reason to prefer one over the other.
Thanks John! Good to know.