Unnecessary Costs from Unused Lambda Versions with SnapStart

Jake McCracken

Service Category

Compute

Cloud Provider

AWS

Service Name

AWS Lambda

Inefficiency Type

Version Sprawl

Explanation

Many teams publish new Lambda versions frequently (e.g., through CI/CD pipelines) but do not clean up old ones. When SnapStart is enabled, each of these versions retains an active snapshot in the cache, generating ongoing charges. Over time, accumulated unused versions can significantly increase spend without delivering any business value. This problem compounds in environments with high deployment velocity or many functions.

Relevant Billing Model

Lambda SnapStart incurs charges for caching snapshots associated with each published function version. Even if a version is no longer invoked, the snapshot cache continues to accrue cost until explicitly removed.

Detection

Review the number of published Lambda versions with SnapStart enabled across accounts
Assess whether older versions are still being invoked or if they remain idle but cached
Correlate Lambda costs with the number of SnapStart-enabled versions retained in each environment
Check for environments with frequent deployments where unused versions may accumulate

Remediation

Delete unused Lambda function versions with SnapStart enabled to eliminate unnecessary cache charges
Implement version lifecycle management practices in CI/CD pipelines to automatically clean up old versions
Retain only the most recent versions required for rollback or audit purposes
Monitor the number of SnapStart-enabled versions per function and enforce limits to prevent sprawl

Relevant Documentation

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