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Polymer / polymer-starter-kit

A starting point for Polymer apps

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Sub par performance on lighthouse in Chrome v62 for `es6-unbundled` build

andrewspy opened this issue · comments

commented

Description

Sub par performance on lighthouse in Chrome v62 out of the box in localhost setup, using polymer init and polymer serve.

Expected outcome

lighthouse performance should be in the 90+/100. With first pain/interactive within few sec, with a Perceptual Speed Index of less than 1,250.

Actual outcome

lighthouse performance index of only 30/100. With first paint/interactive at 13+/13+ sec respectively, with a Perceptual Speed Index of 14,000.

Live Demo

N/A

Steps to reproduce

  1. polymer init with polymer-starter-kit v3.2
  2. polymer serve
  3. Audit with lighthouse in Chrome v62

Browsers Affected

  • Chrome
  • Edge
  • Firefox
  • IE 11
  • Safari 8
  • Safari 9
commented

Did you build the project for production? You should have this score:

Lighthouse Report

Results for: https://psk-demo-6e320.firebaseapp.com
Report: https://builder-dot-lighthouse-ci.appspot.com/report.1510755493877.html

Category Score
Progressive Web App 100
Performance 93
Accessibility 100
Best Practices 94

Tested with Lighthouse version: 2.5.0

Hosted in Firebase. Preset: es5-bundled.

commented

@abdonrd Thanks for the reference on #1071, which I have missed the step of building for production.

I guess the major problem I am having with my build is I'm using es6-unbundled build, which has "Critical Request Chain" of 87 (instead of 2 for es6-bundled).

Given that I am hosting my PWA in Firebase Hosting (which support HTTP/2), should I target my build to es6-bundled? I though es6-unbundled can take advantages of Server Push support in HTTP/2? Does it mean there is a trade-off for having faster first paint vs granular Server Push?

commented

The polymer-build has an issue to improve the push-manifest.json: https://github.com/Polymer/polymer-build/issues/260

Meanwhile, in the Polymer/shop I see some scripts: Polymer/shop#145

commented

@abdonrd Do you know if there is there any plan to resolve the shortfall of having es6-unbundled build? At this stage, es6-unbundled build simply doesn't pass the audit of lighthouse out of the box...