mod_pagespeed filters

add_head - ensures that <head> tag is always present before after
extend_cache - makes sure that everything is cached, make sure that your scripts do not do something like btn.style.backgroundImage = 'hover.png' before after
collapse_whitespace - minifies HTML, make sure that there is no white-space: pre in styles before after
insert_dns_prefetch - inserts <link rel="dns-prefetch" href="//example.com"> to boost DNS lookups before after
remove_comments - avoid it if your JavaScript uses HTML comments before after
remove_quotes - removes unnesessary quotes, savings may be less than time taken before after
trim_urls - removes unnesessary url prefixes, requires rewrite_css before after
elide_attributes - removes unnesessary attributes, avoid it if your styles contains something like input[disabled="disabled"] {...} before after
combine_heads - if for some reason you have multiple head tags in your HTML, this filter will combine them, move_css_to_head is required before after
local_storage_cache - magic before after
rewrite_images - image optimizations before after
lazyload_images - load images after DOM before after
resize_images - to given dimensions, resize_rendered_image_dimensions takes precedence over it before after
resize_rendered_image_dimensions - to actual dimensions, takes precedence over resize_images before after
sprite_images - from css backgrounds before after
inline_preview_images - if there is many images, HTML can be bloated before after
combine_css - combines multiple stylesheets into one file before after
rewrite_css - minify css before after
flatten_css_imports - inlines css imports less, can brake styles under different media queries, requires rewrite_css before after
inline_css - inlines small stylesheets, less than ModPagespeedCssFlattenMaxBytes, which is 2kb by default, can be configured in /etc/apache2/mods-enabled/pagespeed.conf before after
inline_google_font_css - optimize google web font before after
move_css_to_head - makes sure that all styles are int the head before after
move_css_above_scripts - makes sure that all styles are defined before scripts, move_css_to_head is required before after
rewrite_style_attributes - optimizes inline styles, you really should avoid them at all before after
outline_css - outlines big styles to external file, reverse of inline_css before after
prioritize_critical_css - inlines critical css before after
rewrite_javascript - minify javascript before after
inline_javascript - inline small javascript that is less than ModPagespeedJsInlineMaxBytes (2kb by default) before after
combine_javascript - combines multiple javascript files into one before after
insert_ga - automatically add Google Analytics code to all pages before after
outline_javascript - extracting big inline javascript into external file, reverse to inline_javascript before after
defer_javascript - magic before after