While they do point out Ilya's comment in an update, it should be more central:

    Here's a slightly modified MPS config that gets you to
    100 without any manual work:

      ModPageSpeed on
      ModPagespeedRewriteLevel CoreFilters
      ModPagespeedEnableFilters prioritize_critical_css
      ModPagespeedEnableFilters defer_javascript
      ModPagespeedEnableFilters sprite_images
      ModPagespeedEnableFilters convert_png_to_jpeg
      ModPagespeedEnableFilters convert_jpeg_to_webp
      ModPagespeedEnableFilters collapse_whitespace
      ModPagespeedEnableFilters remove_comments

-- https://github.com/danriti/bootstrap-pagespeed/issues/4

mod_pagespeed can automate all those complicated steps.

(Disclaimer: I work on mod_pagespeed and ngx_pagespeed.)