The One HttpClient Mistake That Can Slow Down Your Entire .NET API

Abhishek Joshi

5 min read

·

Oct 7, 2026

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The API was fast in development.

Then traffic increased — and a few innocent lines of C# became the bottleneck.

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At 11:08 AM, the monitoring dashboard at a fictional e-commerce company, Northstar Retail, turned red.

API latency had jumped from 200 ms to several seconds.

SQL Server was healthy. CPU was normal. Redis was fine.

The team initially blamed the database.

They were wrong.

The problem was hiding inside a frequently executed method:

public async Task<Customer?> GetCustomerAsync(int id)
{
    using var client = new HttpClient();
    var response = await client.GetAsync(
        $"https://customer-api/customers/{id}");
    return await response.Content
        .ReadFromJsonAsync<Customer>();
}

It looked harmless.

It wasn’t.

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The HttpClient Trap

Many developers think of HttpClient like this:

Create → Request → Dispose