#### article
## Get to know new, crucial performance metrics
Numerous new performance metrics are being introduced to portray user experience better. In her article, [Milica Mihajlija](https://twitter.com/bibydigital) explains how they are calculated, what they represent, and how they will affect your Lighthouse/PageSpeed Scores.
[]()[The New Generation of Performance Metrics for Better User Experience →](https://calibreapp.com/blog/new-generation-of-performance-metrics)
#### article
## Weigh the implications of self-hosting fonts
Incorrectly handling web fonts can drastically delay rendering of your sites and degrade performance scores. In his post, [Barry Pollard](https://twitter.com/tunetheweb) walks through self-hosting Google Fonts—its challenges, potential benefits and drawbacks.
[]()[Should you self-host Google Fonts? →](https://www.tunetheweb.com/blog/should-you-self-host-google-fonts/)
#### Case study
## How Google built Photos while maintaining 60fps
An excellent case study by [Antin Harasymiv](https://twitter.com/antin), explaining how Google approached building Photos to feel instantaneous. Focusing on perceived performance, the article covers loading strategies, building complex, responsive layouts and 60fps scrolling.
[]()[Building the Google Photos Web UI →](https://medium.com/google-design/google-photos-45b714dfbed1)
#### tools
## Upgrade styled-components for a speed boost
[Evan Jacobs](https://twitter.com/probablyup) announces significant performance improvements to the popular CSS-in-JS library. Amongst others, 26% smaller bundle size and 45% faster server-side rendering. Not too shabby!
[]()[Announcing styled-components v5: Beast Mode →](https://medium.com/styled-components/announcing-styled-components-v5-beast-mode-389747abd987)
#### case study
## How eBay changed its approach to performance
[Senthil Padmanabhan](https://twitter.com/senthil_hi) explains how eBay came to prioritise performance, what goals did they set, and what outcomes did they observe. A fascinating look into a large organisation adopting modern metrics, testing performance prior to releases and even more importantly, introducing Speed Champions to spearhead the effort.
[]()[Speed By A Thousand Cuts →](https://tech.ebayinc.com/engineering/speed-by-a-thousand-cuts/)
#### new in calibre
## What Calibre released last month
📚**Release Notes: December**
Here’s our monthly roundup of what was released in December: New Track a Site Flow, advanced requests filtering, webhook improvements and more.
**⚡️New Site Flow** allows you to set up monitoring faster and easier. Now, you can add multiple pages and adjust the testing schedule in a single step!
[]()
