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Comparing AWS Lambda ARM64 vs. x86_64 Performance Across Runtimes in Late 2025

chrisebert.net

31–40 of 60 posts

Re: Comparing AWS Lambda ARM64 vs. x86_64 Performance Across Runtimes in Late 2025

#31
I tried to do a very low latency https endpoint with Lambda and Rust and wasn't able to get less than 30ms, no matter what I tried.

Then I deoloyed an ECS task with ALB and got something like Has anybody gotten sub-10ms latencies with Lambda Https functions?

Re: Comparing AWS Lambda ARM64 vs. x86_64 Performance Across Runtimes in Late 2025

#32
post #3

Would be interesting to add a cold start + "import boto3" benchmark for Python as importing boto3 takes forever on lambdas with little memory. For this scenario I only know this benchmark but it is from 2021 https://github.com/MauriceBrg/aws-blog.de-projects/tree/mast...

if imports are slow one should probably look into pre-compiling .pyc files into the Lambda bundle

This is a well known issue, and the fix is not to create any boto3 clients at runtime. Instead, ensure they're created globally (even if you throw them away) as the work then gets done once during the init period. The init period gets additional CPU allocation, so this is essentially "free" CPU.

Source: I'm a former AWS employee.

Re: Comparing AWS Lambda ARM64 vs. x86_64 Performance Across Runtimes in Late 2025

#33

I would not be surprised that Rust be faster than Python, but looking at the code of his Benchmarks, I'm not sure that it really means anything. For example, the "light" test will do calls to "dynamodb". Maybe you benchmark python, or you benchmark the aws sdk implementation with different versions of python, or just you benchmark average dynamodb latencies at different times of the day, ... And, at least for Python,…

Sure. Who is to say where the bottleneck is, but if an application is going to use all those same libraries and runtimes, it’s not an unrealistic test. Obviously, with all benchmarking, the most accurate benchmark is your own application, but this seems pretty reasonable as a generic first cut.

Re: Comparing AWS Lambda ARM64 vs. x86_64 Performance Across Runtimes in Late 2025

#34
Something not mentioned in this article is that which x86_64 and arm64 implementation you get are both relatively frozen in time. I haven't checked recently, but the last time I did, the arm64 implementation was stuck at something like Graviton2.

Re: Comparing AWS Lambda ARM64 vs. x86_64 Performance Across Runtimes in Late 2025

#35

Can someone tell me why there isn't almost any laptop with Linux and ARM? Is it more efficient than x86 though

How is the bootloader/peripheral compatibility on the non-SBC ARM systems these days? Can you plug in a boot disk on different machine and expect it to just work? My main problem with ARM is that many manufacturers act as if they're special little snowflakes and deserve to have their custom patched kernel/bootloader/whatever.

This is the goal of the Arm SystemReady compliance label. The selection is still pretty limited and what's out there is generally buggy, but there's a few boards out there you can buy like the Orion O6 [0]. If you just want a stable system with predictable performance, you're probably better off with a more traditional system though.

[0] https://radxa.com/products/orion/o6/

Re: Comparing AWS Lambda ARM64 vs. x86_64 Performance Across Runtimes in Late 2025

#36

One of the easiest hack to reduce your AWS bills is to migrate from x86 to arm64 CPU. Performance difference is negligible, and cost can be upto 50% lower for arm machines. This is for both RDS and general compute (EC2, ECS). Would recommend to all.

How is the performance difference negligible? In my experience, for the same generation of hardware, ARM64 performance is better than the AMD64 one. AFAIK ARM64 is around 20% cheaper, not sure where you got the 50%.

In different regions the price difference is different. In us-east there is a 20% difference, in ap-south it is 50%. You can check for fargate ecs pricing for example.

Re: Comparing AWS Lambda ARM64 vs. x86_64 Performance Across Runtimes in Late 2025

#37
post #9

What I don't get is why is it that Node is dog slow . Seriously it seems borderline unusable. In terms of perf, Node has a pretty snappy JIT, and seems to perform OK in the browser, but this seems like something's not right here. ~200ms requests even in the light case are on the very brink of barely acceptable. On the other hand, Python performs very well, but it's alarming to see it gets slower in every release by a…

> What I don't get is why is it that Node is dog slow. Seriously it seems borderline unusable.

This is in line with my experience using anything written in Node.js

Re: Comparing AWS Lambda ARM64 vs. x86_64 Performance Across Runtimes in Late 2025

#38
post #26

This is benchmarking `hashlib.sha256` isn't that normally OpenSSL's heavily hand optimized assembly implementation, certainly isn't something written in Python?

I think that's the CPU benchmark rather than the python benchmark -- and comparing CPU ARM64 vs x86_64 seems worthwhile.

It is the CPU-Intensive Workload Results; which compares Python versions and notes "Python 3.11 consistently outperformed newer versions across all memory configurations. It was 9-15% faster than Python 3.12, 3.13, and 3.14. This surprised me" The most obvious conclusion is the benchmark is simply flawed in some way; if this result is real, then it says something about how AWS compiled OpenSSL it says absolutely nothing about the speed of Python versions.

Re: Comparing AWS Lambda ARM64 vs. x86_64 Performance Across Runtimes in Late 2025

#39
post #9

What I don't get is why is it that Node is dog slow . Seriously it seems borderline unusable. In terms of perf, Node has a pretty snappy JIT, and seems to perform OK in the browser, but this seems like something's not right here. ~200ms requests even in the light case are on the very brink of barely acceptable. On the other hand, Python performs very well, but it's alarming to see it gets slower in every release by a…

> What I don't get is why is it that Node is dog slow. Seriously it seems borderline unusable. This is in line with my experience using anything written in Node.js

Not on a dedicated server - if serving a db query in a rest endpoint took 100ms in Node, it wouldn't have gotten popular,

In my experience, Node perf is 'okay' - not stellar but a simple express/js handler certainly doesn't take 100ms. This sounds 10x-100x slower than running something similar on a dedicated instance.

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