I believe you may have misunderstood how image compression works. Setting an item to use 10% compression doesn't mean that the output file will be garenteed to be reduced by 10% of it's original file size. There are a lot of additional factors involved in 2hat happens to an image and that's based on what the image contains. Each image is unique. And your JPEG image is probably already somewhat compresses before you even touch it.
https://en.m.wikipedia.org/wiki/JPEGUBB.threads has no control over the version settings of ImageMagick or gd configured on your server. it just takes the image and passes it along to the with the compression/sizing requests, and goes from there.
There is not really much more that can be done to these blanket strings passed from a single command line to every single image that goes through it.
ImageMagick is generally better and handles transparent png/gif files and animated gif files better. GD is a bit quicker and requires slightly less memory and is bundled with current php server package installs.
Beyond that, I'm not really sure what youd like ubb.threads to do, based on your post.
