Next: skip Chromium startup This is complex, as a running browser has open devices, timers, graphics state, network state, and fingerprint state.
Hmm, can't you just keep a set of browsers already running, like a warm pool, ready to assign to an incoming request? The latency would be close to zero for the user. You'd need some prediction logic to expand / contract the warm pool based on traffic patterns, but that seems like the easiest solution to me.