Multi-Model Routing (Fast vs Smart)

Key Concepts

• 1Not every turn needs the most capable model: routing simple interactions to a fast, cheap model and hard ones to a powerful, expensive model optimizes cost and latency together
• 2A router decides per turn (or per task) which model to use, based on complexity signals — a greeting or simple lookup vs a multi-constraint reasoning problem
• 3The savings are large: if most turns are simple, routing the bulk to a cheap model while reserving the expensive one for the few hard cases slashes average CPC
• 4Routing adds a failure mode: mis-routing a hard problem to a weak model produces a bad answer, so the router's accuracy is itself a quality lever
• 5Escalation patterns help: start cheap, and escalate to the stronger model when the cheap one is uncertain or the task proves complex, rather than routing perfectly upfront
• 6Latency benefits too: fast models respond quicker, so routing simple turns to them improves the felt experience on the majority of interactions
• 7Routing is a PM-owned tradeoff: cost and latency savings vs the risk and complexity of misrouting, tuned by monitoring quality per route

Why It Matters for PMs

Test Your Understanding