Bedrock AgentCore runtime V2 flattens cold starts to a P75 near 2 seconds regardless of image size.

Opt in with platformVersion=V2. The old runtime ranged from 5.4 to nearly 30 seconds as image size grew from 200MB to 2GB; the new one holds near 2 seconds across that range. It also reclaims memory when a session goes cold instead of billing peak memory for the session's life, charging a higher rate against far fewer GB-hours. AWS Bursty agents that spike then idle get the biggest win.