font face - Why does this "Slow network detected..." log appear in Chrome?

Question

I noticed this info log began to appear in Google Chrome Dev (Version 55.0.2883.18 dev) and I can't imagine why.

Slow network is detected. Fallback font will be used while loading: http://font-path.extension`

It appears on all websites that use font-face, even on local pages and Chrome extensions.

Answer 1

This means the network is slow, and Chrome is replacing a web font (loaded with a @font-face rule) with a local fallback.

By default, the text rendered with a web font is invisible until the font is downloaded (“flash of invisible text”). With this change, the user on a slow network could start reading right when the content is loaded instead of looking into the empty page for several seconds.

• Related Chrome issue: https://bugs.chromium.org/p/chromium/issues/detail?id=578029. (A change enabling this behavior for 3G connections landed in September; this should be the reason you got the message.)
• Related source code: https://chromium.googlesource.com/chromium/src/third_party/+/master/WebKit/Source/core/css/RemoteFontFaceSource.cpp#74

Answer 2

 i. Adjust the Chrome flag to Unknown:
chrome:/flags/#force-effective-connection-type

 ii. Update Google Chrome to the most recent version. This was a known issue to the ChromeDevTools team, and it appears to be resolved at this time.


 iii. You can also disable this obtrusive notice by using the following options in the Chrome tools:
Console settings -> User messages only

For More Details: https://kodlogs.net/197/slow-network-is-detected-fallback-font-will-be-used-while-loading