AWS launches AgentCore Runtime V2 with elastic memory and snapshot starts

AWS launched Amazon Bedrock AgentCore Runtime V2, a new version of its managed compute layer that can release unused memory and restore initialized agent environments from compact snapshots. Customers can choose it by setting platformVersion to V2 when creating or updating a runtime, AWS said in its launch announcement.

For production agents, the changes reshape how AgentCore allocates resources. A V2 session begins with a smaller resident-memory footprint, brings in more memory as demand rises, and returns memory after an application releases it or the memory becomes cold. AWS’s pricing documentation says idle memory is reclaimed after 120 seconds and memory billing has a 128 MB minimum. Each session still runs in an isolated microVM with its own CPU, memory and filesystem resources. This runtime resource reclamation is distinct from AgentCore memory lifecycle policies for managing stored agent memory.

V2 also changes the cold-start path. AWS launches the container and waits for it to become healthy, then takes a compact snapshot after one-time initialization. New instances restore that snapshot rather than repeat initialization, according to the AgentCore Runtime documentation.

In AWS’s testing, that mechanism kept P75 cold-start latency at about two seconds for container images ranging from 200 MB to 2 GB. The company said the original runtime ranged from about 5.4 seconds to nearly 30 seconds as image size grew. The benchmark used 5,000 cold invocations per agent and an empty echo agent with no model or tool calls. A client in us-west-2 called agents in us-east-1 over the public internet under default account quotas. AWS measured startup from the client side, including the inter-region round trip; the echo code itself ran in about 34 milliseconds at P75. AWS did not publish raw measurements, and the results have not been independently replicated.

Billing follows microVM resources consumed per second, with a one-second minimum. CPU can scale to zero while an agent waits for I/O if no background process is using it, while memory remains billable until it is reclaimed or the session ends. AWS lists V2 at $0.1276 per vCPU-hour and $0.0169 per GB-hour, versus $0.0895 and $0.00945 respectively for V1. The company claims most agents will use sufficiently fewer billed GB-hours to offset the higher unit rates and lower their total bill, but it did not provide independent evidence for that workload-dependent result.

AWS lists committed-baseline discounts, larger compute and storage configurations, x86 microVM support, expanded lifecycle controls and scoped session identity as coming-soon capabilities, not features included in this release.