iOS Simulator bad performance after run flutter upgrade

Question

After upgrade flutter, the performance of iOS Simulator became so bad. for example, slow to launch and slow to show keyboard.

I ran flutter doctor. Here is my result.

$ flutter doctor -v
[✓] Flutter (Channel master, v1.9.8-pre.35, on Mac OS X 10.14.6 18G87, locale ja-JP)
• Flutter version 1.9.8-pre.35 at /Users/rafekun/Developer/flutter
• Framework revision 1363528eee (4 days ago), 2019-08-31 05:26:41 -0400
• Engine revision cd858489cc
• Dart version 2.5.0 (build 2.5.0-dev.4.0 36985859e4)


[✓] Android toolchain - develop for Android devices (Android SDK         version 29.0.0)
• Android SDK at /Users/rafekun/Library/Android/sdk
• Android NDK location not configured (optional; useful for native profiling support)
• Platform android-29, build-tools 29.0.0
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)
• All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 10.3)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 10.3, Build version 10G8
• CocoaPods version 1.7.5

[✓] Android Studio (version 3.5)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin version 38.2.3
• Dart plugin version 191.8423
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)

[✓] VS Code (version 1.37.0)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.3.0

[✓] Connected device (1 available)
• iPhone Xʀ • B3C345C3-5AB0-4627-B854-2C90016A3B69 • ios •
  com.apple.CoreSimulator.SimRuntime.iOS-12-4 (simulator)

• No issues found!

i downgraded flutter SDK to stabler version. However, there are still same problems. — Masahiro Aoki, Sep 06 '19 at 11:11
I found the the solution. Just uncheck "Slow Animation" in Simulator. There are no relations between Xcode simulator and Flutter SDK version. — Masahiro Aoki, Jan 23 '20 at 07:26

score 1 · Answer 1 · answered Nov 01 '20 at 21:18

If you are experiencing slowness, low FPS, laggy scrolling on specific (newer) devices in Xcode simulator that's because Apple dropped support for OpenGL and Flutter SDK does not support the new Metal API in simulators.

But the official stable support will be available soon, until that if you need 60 FPS, switch to the master channel of Flutter SDK by running this in terminal and rebuild your app:

flutter channel master

sources:

iOS Simulator gradually becomes very slow & unusable

Investigate enabling Metal on iOS simulators above version 13.0.

Will Flutter use Metal on iOS Simulators?

iOS Simulator bad performance after run flutter upgrade

1 Answers1