I have found that the gs command running background of imagemagick causes 100% CPU. Here is the command below: gs -q -dQUIET -dSAFER -dBATCH -dNOPAUSE -dNOPROMPT -dMaxBitmap=500000000 -dAlignToPixels=0 -dGridFitTT=2 -sDEVICE=pamcmyk32 -dTextAlphaBits=4 -dGraphicsAlphaBits=4 -r72x72 -dUseCIEColor -dFirstPage=1 -dLastPage=1 -sOutputFile=/tmp/magick-2473h7IyR1jxJov3%d -f/tmp/magick-2473ljRlL1Re3EWV -f/tmp/magick-2473eXbEz6zff2nO
As we released 9.18 around three months ago, you should re-test with the latest version. If it still happens, then reopen this bug, and attach the Postscript or PDF file which causes the problem.