Server-Timing header found 180ms hidden in TTFB

Server-Timing header found 180ms hidden in TTFB
TTFB is a black box until you instrument the server response itself.
— Added Server-Timing headers: db=140ms, cache=8ms, render=22ms, app-boot=180ms
— The 180ms app-boot was an uncached config load running per-request
— Cached it: TTFB 410ms -> 230ms with no query optimization at all
— Server-Timing surfaces in DevTools and RUM, so you see the breakdown in the field, not just lab
You can't optimize a TTFB you can't decompose.
Takeaway: instrument TTFB sub-phases — the biggest slice is rarely the DB.