I Benchmarked Lambda arm64 vs x86_64 on an I/O-Bound Workload So You Don't Have To

Sun, 16 Aug 2026 09:00:00 +0700

Graviton is always pitched as cheaper. I wanted to know if it’s also faster — for a boring, I/O-bound Lambda function, not the CPU-crunching demos AWS likes to show off.

AWS says faster. I don’t do “trust me bro” benchmarks.

AWS markets Lambda on Graviton (arm64) as up to 20% cheaper and faster than x86_64 for “most workloads.” Most of the public benchmarks backing that up are CPU-bound — image compression, number crunching, that kind of thing. But most Lambda functions running in production aren’t doing math, they’re doing I/O: call DynamoDB, call S3, call some other API, then wait.

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I Benchmarked Lambda arm64 vs x86_64 on an I/O-Bound Workload So You Don't Have To