dev-server-hmr makes rendering 2x slower after each rerender

[bashmish]

Expected behavior

HMR does't add huge performance hit, making every next rerender 2x slower

Actual Behavior

A combination of components makes rendering 2x slower each time.
Reproduction: https://github.com/bashmish/bug-slow-open-wc-hmr => npm i && npm start

Monosnap.screencast.2024-02-01.16-55-01.mp4

Additional context

This is due to the UpdatingElement which get's registered by the HMR logic, because it extends HTMLElement.
In Lit 3 same happens with ReactiveElement.
If you disable the HMR plugin, the UI works fast and consistently fast.

I deliberately added "node_modules/lit-element/node_modules/@lit/reactive-element/**" in the reproduction to include, although in real life my setup is more complex and UpdatingElement is bundled together with MyElement and the bundle is loaded as a single file, so include / exclude file matcher are not helpful as a workaround.

I made this simple commit with a test to illustrate this behavior: e2147a3
This test will fail

  1) babelPluginWcHmr - detecting base class
       global base class:

      AssertionError: expected 'import * as __$wc_hmr$__ from \'/__we…' to equal 'import * as __$wc_hmr$__ from \'/__we…'
      + expected - actual

       if (import.meta.hot) {
         import.meta.hot.accept();
       }
       let Foo = __$wc_hmr$__.register(import.meta, "Foo", class Foo extends MyElement {});
      -;
      -let UpdatingElement = __$wc_hmr$__.register(import.meta, "UpdatingElement", class UpdatingElement extends HTMLElement {});
      -;
      +class UpdatingElement extends HTMLElement {}

      at Context.<anonymous> (packages/dev-server-hmr/test-node/babel/base-class.test.js:13:23)
      at process.processImmediate (node:internal/timers:478:21)

Documentation https://open-wc.org/docs/development/hot-module-replacement/#detecting-web-components says however that:

By default we look for usage of customElements.define and/or classes that derive from HTMLElement directly.

So it seems to be an expected behavior, but not clear why.

Proposal

Some ideas:

• do not automatically register all classes extending from HTMLElement (not sure why this is done by default? I did see different specs, but they focus on other more specific cases, e.g. with customElements.define, so still not clear to me)
• add "excludeClass" to specify classes which shouldn't be registered and add UpdatingElement/ReactiveElement to lit presets