webperf - "performance opportunities" per Lighthouse

[mohawk2]

https://webpagetest.org/lighthouse.php?test=200615_WM_8d77c5a1320cf7af7badb20f6f423515&run=1 shows these opportunities to improve:

• [x] Consider using <link rel=preload> to prioritize fetching resources that are currently requested later in page load (on the various woff2 resources) - save 1.68s
• [ ] Resources are blocking the first paint of your page. Consider delivering critical JS/CSS inline and deferring all non-critical JS/styles (the generated JS and CSS asset files) - save 1.17s
• [ ] Remove unused JavaScript to reduce bytes consumed by network activity (it's saying Google Analytics and half of the JS asset file are unused) - save 0.7s
• [x] Consider adding preconnect or dns-prefetch resource hints to establish early connections to important third-party origins (https://www.google-analytics.com, https://stats.g.doubleclick.net) - save 0.55s
• [ ] Remove dead rules from stylesheets and defer the loading of CSS not used for above-the-fold content to reduce unnecessary bytes consumed by network activity (says ~90% of the CSS asset is unused) - save 0.52s
• [ ] Image formats like JPEG 2000, JPEG XR, and WebP often provide better compression than PNG or JPEG, which means faster downloads and less data consumption (sponsors/yellowbot.png, sponsors/liquidweb_color.png) - save 0.52s
• [x] also says sponsors/yellowbot.png could be "properly sized"
• [ ] Minifying CSS files can reduce network payload sizes (the generated CSS asset) - save 0.17s

[mohawk2]

To capture what the overall test (https://webpagetest.org/result/200615_WM_8d77c5a1320cf7af7badb20f6f423515/) said, in case it goes away:

Lighthouse Perf was 58:

Metric	value
First Contentful Paint	2.4 s
Speed Index	2.5 s
Largest Contentful Paint	3.6 s
Time to Interactive	2.4 s
Total Blocking Time	0 ms
Cumulative Layout Shift	0

[mohawk2]

State of play is now this (https://www.webpagetest.org/result/200620_FC_18726293a28543ae5c46dd91e07dbefe/ - with a differently-formatted URL, confusingly). Showing much better numbers thanks to @haarg fixing #2310. The big win showing there now is the <link rel=preload> on https://metacpan.org/static/fonts/fa-regular-400.woff2, claiming a 2.2s gain available.

[mohawk2]

Not yet reported here, and giving slightly different suggestions, is the Lighthouse report for the front page rather than for a module: https://www.webpagetest.org/result/200620_YD_c3ac0c1118d819f02bb58894a5673945/

[mohawk2]

Latest results after the preload merge: https://www.webpagetest.org/result/200627_H1_cdb0345c7dbbe92feb82dead41024788/ (the content has changed slightly)

Metric	value
First Contentful Paint	1.5 s
Speed Index	1.5 s
Largest Contentful Paint	1.5 s
Total Blocking Time	>= 0.1 s
Cumulative Layout Shift	0
Document Complete	2.5 s