Last updated: May 2021 Table Of Contents Introduction How was it done before? How to use 3.1 Interlude: PerformanceTimeline 3.2 ResourceTiming 3.3 Initiator Types 3.4 What Resources are Included 3.5 Crawling IFRAMEs 3.6 Cached Resources 3.7 304 Not Modified 3.8 The ResourceTiming Buffer 3.9 Timing-Allow-Origin 3.10 Blocking Time 3.11 Content Sizes 3.12 Service Workers 3.13 Compressing ResourceTimi
