When in flight mode on Android, Chromium browsers display content very slowly #781
Description
This may be related to #611, but in Android, when the device is fully offline (flight mode), there appears to be a long timeout for failing network requests in Chromium browsers, resulting in slow performance for the display of pages (most likely because display is delayed until DOMContentLoaded. I should perhaps look into checking if the device is offline before allowing any Fetch requests to go to the network (fail them immediately). Alternatively, see if I should display the article before the content is loaded, at risk of Flash of Incorrect Theme...
As this only occurs with specific ZIMs, I suspect it is due to some content not in the ZIM. However, such content should be caught by the CSP. Alternatively, parts of the app not fully cached? Needs careful debugging.
This does NOT appear to affect Firefox.