1679862 - Investigate the performance impact (if any) of using a non-system font for the browser UI.

Status: RESOLVED FIXED

(Firefox :: Theme, task)

Description

[Mike Conley (:mconley) (:⚙️)]

This bug will mainly focus on identifying any performance concerns with loading and using a non-system font for the browser UI.

Comment 1

[Mike Conley (:mconley) (:⚙️)]

Hey ckerschb,

It doesn't look like the about:home/about:newtab CSP allows me to load fonts from chrome:// URIs. I've tried adding font-src to the CSP rules for that page, but no dice. Do you know if what I'm trying to do is even possible right now?

Comment 2

[Mike Conley (:mconley) (:⚙️)]

Here's a try build testing the Metropolis font across the board in the browser UI and in about:home. I'm using a pretty aggressive * {} CSS rule and web fonts to pull this off, so this will hopefully give us an upper bound on any kinds of performance impacts here.

https://treeherder.mozilla.org/jobs?repo=try&revision=7f6538beac59865f8651c2ca57235f624102ae42

Base revision: https://treeherder.mozilla.org/jobs?repo=try&selectedTaskRun=J9C4z3v9SwWU0cVElOPQ3w.0&revision=7f6538beac59865f8651c2ca57235f624102ae42

Comparison: https://treeherder.mozilla.org/perfherder/compare?originalProject=try&originalRevision=50c5e011e625821d9ada0f77b54e0e12d2993835&newProject=try&newRevision=7f6538beac59865f8651c2ca57235f624102ae42&framework=1

Comment 3

[Mike Conley (:mconley) (:⚙️)]

I found a solution to loading the built-in font inside of in-content pages by modifying the channel building routine in FontPreloader. ckerschbaumer said it looks like the right idea in another communications channel, so clearing ni.

Comment 4

[Mike Conley (:mconley) (:⚙️)]

We have concluded that changing the default font in the main browser UI will have a number of negative performance impacts. We will not be doing this for now.