dontcallmedom
commented
10 years ago One of the critical items in performance is detecting "first paint". From what I understand, this can be detected via an extension to the Navigation Timing API in Chrome and IE (nt_first_paint); see the Yahoo plugin to expose it: http://www.lognormal.com/boomerang/doc/api/navtiming.html https://dvcs.w3.org/hg/webperf/raw-file/tip/specs/NavigationTiming/Overview.html
In general, Navigation Timing will be a very useful API to make a performance profile of the page.
Unfortunately, it looks like it isn't implemented in phantomjs: https://github.com/ariya/phantomjs/issues/10570
Searching about around this, I've found http://www.sitespeed.io/ which is an open source tool to measure performance that can be configured to apply some specific rules. There may be a lot to be gained by importing that tool in ours (if that's at all possible).
A number of things will block the browser from displaying anything when loading a Web page:
In addition, some other assets will create unwanted artifacts when loading a Web page; the "flash of unstyled text" (often referred as FOUT) due to downloadable fonts (e.g. WOFF) is probably the most well-known of those.
The checker should (as far as possible) give advices on how to reduce or remove these.