PHP Imagick processing images takes long time - php

Question

I'm processing 5MB - 6MB images and reducing them to under 600KB file size using PHP Imagick. Usually on the order of 3000 to 5000 at a time. However, the process is taking 8-12 hours to complete. I tried two different ways of handling this: 1) Retrieving the images remotely using Guzzle Pool and storing them locally, then running the conversion process, and 2) Retrieving the images remotely and storing in an ImageMagick object, processing them, then saving locally. Either method seems to take a huge amount of time to complete. The process of resizing the images and saving them below is the same between the two methods, except for reading the image from file if I already have it saved locally.
$imagick = new Imagick();
$imagick->readImageBlob($source);
$imagick->setImageFormat('jpg');
$imagick->setOption('jpeg:extent', '600kb');
$imagick->stripImage();
$imagick->writeImage($destination);
Wondering if there is something else I can do to speed things up.

Answer 1

I have several suggestions, and you can probably combine them together too if you wish. It would have helped if you had specified your OS and also the image types in your question...
First suggestion - process in parallel
Do them in parallel, with GNU Parallel. So instead of the following sequential code:
for f in *.png; do
./Process "$f"
done
you would do:
parallel ./Process {} ::: *.png
Second suggestion - use "shrink on load"
If you are reducing the pixel dimensions of your images, i.e. from 5,000x3,000 pixels to 800x600 pixels for example, and they are JPEGs, you can use "shrink on load"
magick -define jpeg:size=1600x1200 BigBoy.jpg -define jpeg:extent=600kb BiteSize.jpg
Consider vips
Consider using vips which I suspect will be much faster and lighter on resources
vipsthumbnail BigBoy.jpg -s 800x600 -o BiteSize.jpg
Add --vips-leak to the command above to see how much memory it used.