Nginx PageSpeed PageSpeed recommended filters for Maximum compatibility + speed?

RB1 · Apr 22, 2017

I can't always test my pages on every different browser/configuration/version or I could just be missing some broken pages.
Does anyone have tips on what PageSpeed filters to always avoid and which ones should be safe most of the time to enable?

eva2000 · Apr 22, 2017

troublesome ones are the ones with the biggest benefit to page load performance hehe

they'd be

Prioritize Critical CSS https://modpagespeed.com/doc/filter-prioritize-critical-css

Defer JavaScript https://modpagespeed.com/doc/filter-js-defer

Objective
This rewriter improves page render times by identifying CSS rules needed to render the page, inlining those critical rules and deferring the load of the full CSS resources.

Description
prioritize_critical_css parses the CSS and replaces it with inlined CSS that contains only the rules used on the page. This avoids any blocking CSS requests needed for the initial render. It also collects all CSS tags and appends them to the HTML in the same order they were found. This will make all style rules available after page load.

Deferring style rules that are not used by the document delays downloading unnecessary bytes and allows the browser to start rendering sooner per this best practice.
Click to expand...
Description
Warning: Defering JavaScript can often dramatically improve the rendering speed of a site, but careful evaluation is required to ensure the site continues to operate properly. The limitations are described below.

defer_javascript tries to defer JavaScript execution until page load. It defers this by changing the type and srcattributes of <script> elements on the HTML page to data-pagespeed-orig-type and data-pagespeed-orig-srcrespectively. It also adds a new type attribute whose value is set to text/psajs. A window.onload handler is added to the HTML, which executes all the deferred scripts.

defer_javascript doesn't defer a script tag if it has the data-pagespeed-no-defer attribute (preferred) or pagespeed_no_defer attribute (deprecated). This is useful when a script tag needs to be executed while loading the page. For example, a script tag may be updating the main content dynamically as a slideshow of images in the visible content of the page. Usage:
Code (Text):
<script data-pagespeed-no-defer>...</script>
Click to expand...

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Nginx PageSpeed PageSpeed recommended filters for Maximum compatibility + speed?

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