A Tune challenge from Strava. Sunday morning: everyone is back from their long run, and 115 activities a second are being saved, five times a normal day. Runners wait half a minute to see their run. Show each runner their activity within 3 seconds and time their segments within 30, lose no upload, change only settings, and spend as little as you can.
The design you start with: p99 198ms, 0% of requests failing, 704/s answered.