Three-day study
Cold-start timing study
Timed icon-to-interactive measurements on agreed device classes, with a short note on what still runs before the first useful paint.
We record from the moment the icon is tapped to the first frame the person can scroll or type. Splash branding that hides a blocked network call is called out as waiting, not as design.
You receive a table of timings (median and slowest of ten runs) per device, plus a paragraph on each expensive step we could see without opening your source. Useful before a festive campaign when you already know login is the complaint, but not why.