Version:
deno 2.3.5 (stable, release, x86_64-unknown-linux-gnu)
v8 13.7.152.6-rusty
typescript 5.8.3

We’re experiencing performance issues when using the AWS SDK in Deno, specifically with DynamoDB operations. We noticed that:

• Initial connections to AWS can take up to 1.5 seconds
• A basic operation like ListTablesCommand takes around 130 ms

While these numbers may seem reasonable, they are approximately 3× slower than the same operations in Node.js or Bun. This has a measurable impact on infrastructure costs, as we need to scale more aggressively when under load.

We used Vegeta to benchmark this setup with the following command:

echo 'GET http://localhost:8080' | ./vegeta attack -rate=50/1s -duration=5s -timeout=5s | tee results.bin | ./vegeta report

Minimal reproduction code:

import { DynamoDBClient, ListTablesCommand  } from "@aws-sdk/client-dynamodb";
const client = new DynamoDBClient({
  region: "us-east-1", // Adjust this to your AWS region
  // requestHandler: new NodeHttpHandler({
  //   httpsAgent: new Agent({
  //     keepAlive: true,
  //     maxSockets: 100,
  //   }),
  // }),
});
Deno.serve({
  port: 8080,
}, async (req) => {
  try {
    await client.send(new ListTablesCommand({}));
    return new Response("ok");
  } catch (error) {
    console.error("Failed to query:", error);
    return new Response("Error querying DynamoDB", { status: 500 });
  }
});

• Tried using a custom requestHandler with keepAlive settings with no noticeable improvement.
• Similar latency was observed when using the EC2 SDK to list available regions.
• The issue seems related to the networking stack or HTTP client layer used by Deno.

Question

Is this expected behaviour, or is there something we could do to improve performance when using the AWS SDK in Deno? Happy to provide more details or run additional diagnostics if helpful.