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Webview postMessage slow in Release/Production build

See original GitHub issue

I have reviewed the documentation
I have searched existing issues
I am using the latest React Native version

I’m using a webview to send click events back to react-native. When building for debug, the time to receive the message is quick ( 0.5 seconds), but when building for release/production the time is ~ 5 seconds in the simulator and ~10 seconds on device. I have also tried using react-native-wkwebview-reborn with the same result.

Environment

OS: OS X El Capitan 10.11.6 Node: 6.4.0 Yarn: Not Found npm: 3.10.3 Watchman: 4.6.0 Xcode: Xcode 8.0 Build version 8A218a Android Studio: 2.1 AI-143.3101438

Packages: (wanted => installed) react: 16.0.0 => 16.0.0 react-native: ^0.51.0 => 0.51.0

Steps to Reproduce

index.html

<script>
    function sendMessage(){
        window.postMessage('{"key":' + 1 +'}')
    }
</script>
<body>
    <button onclick='sendMessage()'>
        Send 
    </button>
</body>

index.js

onWebViewMessage(event) {
    console.log("Message received from webview", event);
  }
....
<WebView
            ref={webview => {
              this.myWebView = webview;
            }}
            scrollEnabled={true}
            source={require("./index.html")}
            onMessage={this.onWebViewMessage}
            style={{flex: 1}}
   />

Expected Behavior

Similar performance and speed to debug.

Actual Behavior

Much slower.

Issue Analytics

State:
Created 5 years ago
Comments:7 (1 by maintainers)

Top GitHub Comments

2reactions

Karasynthcommented, Mar 22, 2018

I haven’t had the chance to update to Sierra/XCode9, running into the same issue here when building: https://github.com/facebook/react-native/issues/18238

Could someone try to reproduce in 0.54?

Edit: Got it running in 0.53, same behaviour though.

1reaction

sambernaerdtcommented, Jun 15, 2018

Hi, just want to let you know that I’m having the same issue.

Fetching data from the server goes fast (<1s) when running in debug mode with Remote JS Debugging enabled. If Remote debugging is disabled or running the release version, the same action takes >10s.

Using “react-native”: “0.55.4”

I don’t know if it’s related to this issue, but I’m using “cross-fetch”: “^2.2.0” to fetch data.

It would be great if anyone knows how to solve this… Thanks.

EDIT: The problem was related to something else. There was still some logging enabled in the release version which caused the performance hit. Without logging, everything runs silky smooth…