In order to make the comparison as equivalent as possible, I enabled/disabled all the following filters.
ModPagespeedDisableFilters in_place_optimize_for_browser
ModPagespeedEnableFilters add_head
ModPagespeedEnableFilters combine_css,combine_javascript,
ModPagespeedEnableFilters convert_gif_to_png,convert_jpeg_to_progressive,convert_jpeg_to_webp,convert_meta_tags,convert_png_to_jpeg,convert_to_webp_lossless
ModPagespeedEnableFilters extend_cache,extend_cache_css,extend_cache_images,extend_cache_scripts
ModPagespeedEnableFilters fallback_rewrite_css_urls,flatten_css_imports,inline_css
ModPagespeedEnableFilters inline_images,inline_import_to_link,inline_javascript
ModPagespeedEnableFilters jpeg_sampling,recompress_images,recompress_jpeg,recompress_png,recompress_webp,resize_images,resize_rendered_image_dimensions
ModPagespeedEnableFilters rewrite_css,rewrite_images,rewrite_javascript,rewrite_javascript_external,rewrite_javascript_inline,rewrite_style_attributes_with_url
ModPagespeedEnableFilters strip_image_color_profile,strip_image_meta_data