further optimize static images

.github/workflows/gh-pages.yml

@@ -34,13 +34,16 @@ jobs:
     # Put a bow on top of Hugo's automatic image processing by using
     # pngquant and jpegoptim to optimize/compress images in posts,
     # just a little lossily (is that a word?)
+    # 
+    # TODO: Find a way to cache the results, this takes about 4 minutes
+    #       each build -- not ideal. Maybe use @sindresorhus/imagemin.
     - name: Optimize processed images
       run: |
         sudo DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends jpegoptim pngquant optipng
         cd $HOME/gh-pages/notes
         find . -iname "*.jp*" -print0 | xargs -0 jpegoptim --max=80 --strip-all
         find . -iname "*.png" -print0 | xargs -0 pngquant --quality=50-70 --speed 3 --ext=.png --force
-        find . -iname "*.png" -print0 | xargs -0 optipng -o2 -force -strip all -quiet --
+        find . -iname "*.png" -print0 | xargs -0 optipng -o3 -force -strip all -quiet --
       # Ignore errors - override pipefail
       shell: bash {0}