slow response time with generated csharp (c# .net)

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Sending my simple get request with Postman takes max 430ms on the first request, and 40-30ms for repeated.
But using the generated c# classes, it takes 40000-50000ms in both async and non-async operations for the same request.
repeated takes 71-74ms, which is faster but double than Postman. after repeating the same request 5 times, I sent a different request that took 120+ms and 90+ms on repeat.

Trying the same thing with NSwag, I get the same initial delay, but repeated request takes 22-25ms.

• 40+ seconds is way too long for an initial request. (max 500ms expected)
• 70+ms for repeated requests is longer than expected for repeated requests. (max 50ms expected)

openapi-generator version

7.0.1

OpenAPI declaration file content or url

note that the yaml was simplified and unused components and paths were removed.

openapi: "3.0.3"
info:
  title: Client API
  version: "2.0"
security:
  - ProjectId: []
components:
  securitySchemes:
    ProjectId:
      description: >
        The ID of the project.
      type: apiKey
      in: header
      name: project-id
  schemas:
    error:
      type: object
      properties:
        message:
          type: string
    uuid:
      type: string
      format: uuid
    project:
      type: object
      required: [id]
      properties:
        id:
          $ref: "#/components/schemas/uuid"
  responses:
    badRequest:
      description: Invalid request
      content:
        application/json:
          schema:
            $ref: "#/components/schemas/error"
    unauthenticated:
      description: Authentication failure
      content:
        application/json:
          schema:
            $ref: "#/components/schemas/error"
    serverError:
      description: Internal server error
      content:
        application/json:
          schema:
            $ref: "#/components/schemas/error"
paths:
  /project:
    get:
      operationId: getProject
      summary: Get public project info
      responses:
        200:
          description: The project object.
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/project"
        "4XX":
          $ref: "#/components/responses/badRequest"
        500:
          $ref: "#/components/responses/serverError"

Generation Details

This is the code gen command:

java -jar openapi-generator-cli-7.0.1.jar generate -i openapi.yaml -g csharp -o ./GeneratedClient --additional-properties targetFramework=net47,library=restsharp

Steps to reproduce

1. Create and run a server that accepts your guid header.
2. Generate using the info in the Generation Details
3. run C# code:

var client = new Org.OpenAPITools.Api.DefaultApi("https://client.api.myserver.com/");
client.Configuration.DefaultHeaders.Add("project-id", "00000000-0000-0000-0000-000000000000");
Console.WriteLine(client.GetProject().ToString());

Note that I have replaced address and guid with generic values. The timing logs are also removed to make it easier to read.

Related issues/PRs

https://stackoverflow.com/questions/72814123/openapi-generator-c-net6-extremely-slow-http-requests-under-certain-condi
https://stackoverflow.com/questions/754333/why-is-this-webrequest-code-slow

Suggest a fix

I believe that the issue of the initial reqest is that the request is configuring or auto-detecting proxies. This issue is also in NSwag.

request.Proxy = null;

Reproduce the generated C# client from the supplied OpenAPI YAML using the 7.0.1 command with library=restsharp, then compare its first and repeated request timings with Postman and NSwag. Inspect the generated client's request and proxy configuration, including the suggested request.Proxy setting. Done means the initial request is near the reported 500ms expectation and repeated requests are near 50ms without breaking normal requests.