Moving median for first paint dropped on 26th/27th April as did total page load time for 95th and 99th percentile. CSS dropped for Barack Obama/Facebook around this time. Webpagetest runs showed no change in first paint.
Could the CSS drop be related to the real world device data or is this just relating to our instrumentation?
During this period there are several changes that may have caused this:
- We broke MediaWiki:Mobile.css (that however loads via JS so unlikely to be related)
- Various CSS was moved off the critical path: https://gerrit.wikimedia.org/r/427703, https://gerrit.wikimedia.org/r/425705 (merged 20th and 25th) and https://gerrit.wikimedia.org/r/425704 https://gerrit.wikimedia.org/r/425703 (merged 12th) but all these don't seem to match the timeframe but maybe caching is related?
Any way we can work out what caused this and do more of it?