** Disclaimer** This information might be inaccurate, due to it being generated automatically
In packages/addon-a11y/src/register.ts, wrap the axe initialization so it only runs in story mode. For example, add a helper:

function isDocsMode() {
return Boolean(document.body.getAttribute('data-is-docs'));
}

Then conditionally init axe:

if (!isDocsMode()) {
// Existing axe.js initialization
}

This disables axe.js in docs mode.

Since the change was no effort (besides having tons of issues with the Storybook repo setup...) I already created a PR.
Feel free to deny the PR, if you think running addon-a11y in docs mode make sense.

I'll try to create a repo with a relatively complex component (let's hope AI can help me out..) and try to reproduce the slow, if so

Can confirm the same issue, it came suddenly in the last few weeks. One table heavy docs page freezed completely. Seeing axe in the performance panel as the culprit.

I've found that instead of disabling the complete addon, another workaround was to set the globals.a11y.manual to true, so that the accessibility addon panel can still be run via click on the little button in the story view.

Hint: We had the issues suddenly without upgrade being on SB Angular 8.5.5 for a while, but persisted after upgrading to 8.6.10

We’re experiencing the same issue with large stories/components (like a MUI Table).

The browser almost freezes when rendering the story. Hover effects and interactions appear tens of seconds, making it nearly unusable.

Option 1:

Disabling addon-a11y "resolves" the issue for us as well.

const config: StorybookConfig = {
  addons: [
    // '@storybook/addon-a11y',
    ...
  ],
  ...
};

Option 2:

Setting globals.a11y.manual to true (as suggested by @smlimasu) fixes the issue.

const preview: Preview = {
  parameters: {
    globals: {
      a11y: {
        // Optional flag to prevent the automatic check
        // It fixes the issue with the a11y addon freezing
        // cf. https://github.com/storybookjs/storybook/issues/30975
        manual: true,
      },
    },
  }
}

However, according to @valentinpalkovic 's comment here, this setting will be removed in v9. So it's probably not a future-proof solution.

Not relevant anymore, since parameters.a11y.manual does not exist anymore in SB 9.0

@guicara Typo in your comment. I think you mean globals.a11y.manual not parameters.globals.a11y.manual.

globals.a11y.manual will not be removed in 9. parameters.a11y.manual will. Sorry for the confusion.

@shilman Indeed, you're right!

I saw this add-on clearly blocking the main thread on Chrome's Performance profiler. TY!