Warm vs cold: where a sync webhook's time goes

Cold is the first request on a fresh worker that has never seen this flow. Installing pieces and booting the engine dominate. After it, the worker is warm.

0

0.5s

1.0s

1.5s

2.0s

Warm

the normal case

~0.2 s

Cold

first request,
fresh worker

Queue + route

~0.4 s

Install pieces

~0.5 s

Boot engine

~0.9 s

~2 s

Queue + route to a worker

Install pieces (bun install)

Fetch flow bundle

Boot engine (fork + isolated-vm)

Run flow

A worker restart wipes its cache, so its first request is cold again. Keep workers warm with AP_REUSE_SANDBOX=true and a pre-sized fleet.