$ convert derp1383201.png derp1383201.ppm
$ time cjpeg -quality 90 -optimize derp1383201.ppm > derp1383201_libjpeg90.jpg
real 0m0.041s user 0m0.037s sys 0m0.004s
$ time guetzli -quality 90 derp1383201.png derp1383201_guetzli90.jpg
real 3m0.546s user 2m57.630s sys 0m2.417s
$ ls -l derp*.jpg
-rw-r--r-- 1 dosamp dosamp 225513 Mar 17 15:29 derp1383201_guetzli90.jpg
-rw-r--r-- 1 dosamp dosamp 227455 Mar 17 15:23 derp1383201_libjpeg90.jpg