Performance drop when updating versions to OpenAPI 3.1.0

[otionstem]

Q&A (please complete the following information)

• OS: macOS (also Windows)
• Browser: chromium (Brave - but any browser)
• Version: 131.0.6778.69 (1.73.89)
• Method of installation: npm
• Swagger-UI version: 5.1.0 - 5.18.2
• Swagger/OpenAPI version: OpenAPI 3.1.0

Content & configuration

Angular project using swagger-ui-dist:5.18.2

Example Swagger/OpenAPI definition:
N/A - large definition (11mb)

Swagger-UI configuration options:

import {SwaggerUIBundle} from 'swagger-ui-dist';

SwaggerUIBundle({
  spec: spec,
  domNode: this.swaggerEle.nativeElement,
  deepLinking: false,
  docExpansion: 'none',
  defaultModelExpandDepth: 3
})

Describe the bug you're encountering

UI performance issue when clicking on each endpoint and viewing its contents.

To reproduce...

Steps to reproduce the behavior:

1. On Swagger UI
2. Click to open a service
3. Click to open an endpoint
4. Loading icon hangs for ~6 seconds

Expected behavior

Endpoint information displays promptly without excessive delays.

Screenshots

Additional context or thoughts

Updating to swagger-ui-dist:5.18.2 (from 4.19.1) there is a UI performance issue when clicking on each endpoint and viewing its contents. Loading icon hangs for ~6 seconds, see screenshot. Once content loads, performance for that expansion is good. Issue persists on OpenAPI 3.1.0 spec but not OpenAPI spec < 3.1.0. I've reviewed a similar issue thread here: #8606 - tested swapping our spec for twitter's (https://gist.github.com/char0n/0623cf602c23de8628b7e06012cfbf00) but issue still persists. We've tested swagger-ui-dist versions between 5.1.0 to 5.18.2 and the performance seems to degrade as the version increases. Oddly enough, as a workaround, we've discovered by manually overriding the 'openapi' value within the spec before initializing, the performance issued is resolved and the UI operates as expected.

Eg.

SwaggerUIBundle({
  spec: {
  	...spec,
  	openapi: '3.0.3'
  },
  domNode: this.swaggerEle.nativeElement,
  deepLinking: false,
  docExpansion: 'none',
  defaultModelExpandDepth: 3
})

Is there some configuration flag to handle this performance issue? Are there unforeseen consequences for overriding the openapi version?

[char0n]

Hi @otionstem,

I'm not able to reproduce on https://gist.github.com/char0n/0623cf602c23de8628b7e06012cfbf00. You seem to be seeing the issue on twitter API as well - for me it's instant on https://petstore3.swagger.io/ (when loading the OpenAPI Description).

I think what we're seeing here is a described in #9513 (comment), section "Cycles (circular references)", but without testing on your actual definition it's impossible to tell. I can create a recipe for you using ApiDOM dereferencing and you can report back how long the dereferencing took. Would that work for you?

Attaching related issues:

• UI crashes on complex OpenAPI documents #9513
• OpenAPI 3.1.0 support: Performance drop when changing versions from latest stable to 5.0-alpha #8606

[otionstem]

I can create a recipe for you using ApiDOM dereferencing and you can report back how long the dereferencing took. Would that work for you?

Sure I'll give it a shot, thanks.