Extremely slow performance

How long does it take for you to compress a couple of images?

I tried compressing a 7,8MB JPG with --quality 84 and it took nearly 20 minutes.

I also tried a 1,4MB JPG with --quality 85 and it took nearly 10 minutes.

I must assume that this is not normal - is something wrong with my binary?

I am on Ubuntu 16.04 LTS, intel core i7-4790K CPU @ 4.00GHz I installed gflag via sudo apt-get install libgflags-dev and got libpng via sudo apt-get install libpng16-dev. After that I make with no errors.

convert -quality 85 src.jpg dst.jpg runs in under 1 second, if that is any help.

Anyone else experience this?