This will be a fun little lab. Let’s make one self-contained Program.cs you can run from command line and flip between TLS 1.2 and TLS 1.3 without changing code.

We’ll also add a /metrics endpoint so you can see basic latency stats directly from the app.

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1. One-page complete code (Program.cs)

Create a new minimal API:

dotnet new web -n TlsTlsDemoApi
cd TlsTlsDemoApi
Code language: JavaScript (javascript)

Now replace the entire contents of Program.cs with this:

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2. How to run with TLS 1.2 vs TLS 1.3

🔹 Windows PowerShell

Run with TLS 1.2:

$env:TLS_VERSION = "12"
dotnet run
Code language: PHP (php)

You’ll see:

Using: TLS 1.2
Listening on: https://localhost:5001
Code language: JavaScript (javascript)

Run with TLS 1.3:

Stop the app, then:

$env:TLS_VERSION = "13"
dotnet run
Code language: PHP (php)

You’ll see:

Using: TLS 1.3
Listening on: https://localhost:5001
Code language: JavaScript (javascript)

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3. How to “load test” it quickly

You can use Postman, or just use curl loops from command line.

🔹 Simple curl loop (Linux/macOS / Git Bash)

for i in {1..200}; do curl -k -s "https://localhost:5001/ping" > /dev/null; done
Code language: JavaScript (javascript)

🔹 Simple PowerShell loop (Windows)

1..200 | ForEach-Object {
    curl -k -s "https://localhost:5001/ping" > $null
}
Code language: JavaScript (javascript)

Then check metrics:

curl -k "https://localhost:5001/metrics"
Code language: JavaScript (javascript)

You’ll see something like:

{
  "tls": "TLS 1.2",
  "totalRequests": 200,
  "averageDurationMs": 6.3,
  "maxDurationMs": 15.2
}
Code language: JSON / JSON with Comments (json)

Run again with TLS 1.3 and compare:

• averageDurationMs
• maxDurationMs

Under heavier load (larger loops, multiple clients), you’ll see TLS 1.3 usually gives better latency and smoother max values, especially when handshake overhead matters (cold clients).

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4. Where to see CPU / memory

You asked:

“Do we have any way to see the load metrics in the code itself?”

We did that with /metrics (per-request latency). For CPU and memory, best is:

🔹 Option A: dotnet-counters (recommended)

Find PID:

dotnet-counters ps

Then:

dotnet-counters monitor --process-id <PID> System.Runtime
Code language: HTML, XML (xml)

Watch:

• cpu-usage
• gc-heap-size
• gen-0-gc-count etc.

Run your load loop and watch how TLS 1.2 vs 1.3 behaves.

🔹 Option B: Task Manager

Just open Task Manager → Details → dotnet.exe, watch CPU and Memory while you hit /ping.

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5. How to use this in your understanding

1. Start with TLS 1.2 (TLS_VERSION=12).
2. Run a curl/Postman loop, show /metrics.
3. Show CPU/memory with dotnet-counters or Task Manager.
4. Switch to TLS 1.3 (TLS_VERSION=13).
5. Repeat same load → compare metrics.
6. Explain:
   • Less handshake overhead
   • Better latency
   • Lower CPU under same load (especially when doing many short connections).

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