ModuleFederationPluginV2 causes extremely slow app startup on Android mid-range devices #1325

[hndc9x]

Describe the bug

Description

We are experiencing severe performance issues when using ModuleFederationPluginV2 in a React Native application with Re.Pack. The app startup time increases dramatically, especially on mid-range Android devices.

Environment

• Re.Pack version: 5.x (latest)
• React Native: 0.79+
• React: 19.x
• @module-federation/runtime: latest
• Platform: Android (iOS is less affected)
• Bundler: Rspack
• Device: Mid-range Android devices (e.g., Samsung A series, Xiaomi Redmi)

Problems Encountered

1. 🐢 Slow App Startup with ModuleFederationPluginV2

When using ModuleFederationPluginV2 with a large number of shared dependencies (15-30+ packages), the app startup time increases by 5-15+ seconds on mid-range Android devices.

Current config example:

new Repack.plugins.ModuleFederationPluginV2({
  name: "loyalty",
  dts: false,
  remotes: STANDALONE
    ? {
        InvoicePayment: `InvoicePayment@http://localhost:9000/${platform}/mf-manifest.json`,
        HelpCenter: `HelpCenter@http://localhost:9001/${platform}/mf-manifest.json`,
        TrackingOrder: `TrackingOrder@http://localhost:9002/${platform}/mf-manifest.json`,
        MWGShop: `MWGShop@http://localhost:9003/${platform}/mf-manifest.json`,
        UtilityServices: `UtilityServices@http://localhost:9004/${platform}/mf-manifest.json`,
        DMX: `DMX@http://localhost:9003/${platform}/mf-manifest.json`,
        PaymentGateway: `PaymentGateway@http://localhost:8000/${platform}/mf-manifest.json`,
      }
    : {
        InvoicePayment: `InvoicePayment@invoice.container.js.bundle`,
        HelpCenter: `HelpCenter@helpcenter.container.js.bundle`,
        TrackingOrder: `TrackingOrder@trackingorder.container.js.bundle`,
        MWGShop: `MWGShop@mwgshop.container.js.bundle`,
        UtilityServices: `UtilityServices@utility.container.js.bundle`,
        DMX: `DMX@dmx.container.js.bundle`,
        PaymentGateway: `PaymentGateway@paymentgateway.container.js.bundle`,
      },
  shared: {
    ...getSharedDependencies({ eager: true, bundle: false }),
    "react-native-webrtc": { singleton: true, eager: true },
  },
})

### System Info

```shell
npx react-native info

Re.Pack Version

5.2.1

Reproduction

url

Steps to reproduce

Steps to reproduce

[sleeper-luke]

Wanted to add to this that we're seeing the exact same problem!

It basically made the V2 version of the plugin unusable for us, unfortunately. I think it has something to do with v1 doing lazy initialization of shared dependencies, but v2 has to validate all dependencies on startup syncronously (even before actually loading any remote modules) and call loadShareSync() for each one.

I tried a bunch of different solutions, like setting eager to false for shared dependencies but that was causing crashes, since loadShareSync() would fail.

loadShareSync failed! The function should not be called unless you set "eager:true".
Error: Invalid loadShareSync function call from runtime #RUNTIME-006
args: {"hostName":"sleeper","sharedPkgName":"react-native-safe-area-context"}

We have something like 90 shared dependencies because we allow users to create arbitrary remote modules and we never know which dependencies they will or won't use. So in the end I ended up having to revert to V1.

[longb1997]

In the early versions of Repack (5.0.x), we faced the same problem, but after upgrading to 5.1, this bug was resolved.

[jbroma]

Sounds like a problem with MF rather than Re.Pack, so we might need to tackle this upstream, @hndc9x @sleeper-luke could you please provide a reproduction where this is a case? Then we could easily upstream this and get this fixed