A diff is two zit subprocesses on purpose, run at once. Adding their durations printed more time than the whole request took — "rendered in 410.1ms (zit 706.8ms×2)", and "79.94s (zit 159.05s×2)" on a cold tcl page. A number larger than the total reads as a broken page rather than as two calls overlapping.

Record now takes the start instant instead of a duration, because a duration cannot say whether two calls overlapped, and the union of the spans is what a reader actually waited. closed check-in: 4aaf089616 user: dmestas tags: timing-wall