Fixing Slow Build Time in Flutter: Developer-Proven Methods

Estimated Reading Time: 8 minutes

There’s nothing that drains developer productivity more than having to wait for a Flutter build to complete. If you’ve ever found yourself staring blankly at your terminal, going “why on earth does my app take so damn long to compile?”, then know that I feel you. Slow build times are one of the top complaints from people working with Flutter.

The good news? There are tested ways to speed things up without cutting corners on quality. In this guide, we’ll explain why builds can become slow and provide actionable steps for keeping your Flutter flow super-fast!

Overview

The Flutter build includes the Dart code compilation, generating binaries for platform-specific and packaging of assets. This is efficient by many frames, however some things like project size, dependencies and mis-configuration can slow that down.

Knowing such is necessary in order to make the right fixes. Here are some of the main suspects when it comes to slow-building builds.

Common Causes of Slow Build Time

• Heavy Dependencies: The overhead of giant packages and an excess of plugins make for cumbersome builds.
• Unoptimized Assets: There are many images of high-resolutions and even the unused ones that bulge up the build.
• Poorly Configured Gradle Settings: In Android, incorrectly configured Gradle can reduce your build speed to a crawl.
• No Incremental Builds: Full rebuilds instead of hot reload/hot restart take time.
• Debug vs. Release Confusion: Running release instead of debug mode for testing slows down builds.

Step-by-Step Guide to Speed Up Flutter Builds

1. Enable Fast Startup: Run with flutter run --fast-start to increase app startup speed during hot reload.
2. Use Hot Reload: Don’t restart the app; use hot reload as much as possible.
3. Clean Gradle Cache: Run ./gradlew clean periodically to remove old files.
4. Use Split APKs: On Android, allow apps to be packaged for each CPU architecture.
5. Boost Assets: Compress images and eliminate unused resources.
6. Update Flutter & Dart: Performance improvements often come with new versions.

Best Practices for Consistent Speed

• Keep dependencies minimal and updated.
• Prefer const widgets for faster rebuilds.
• Run builds on SSD storage for improved I/O performance.
• Enable Gradle daemon and parallel execution in gradle.properties.
• Use Flutter's build caching for repeated builds.

Pro Tips:

• Run flutter pub cache repair if you suspect dependency issues.
• Use flutter build apk --split-per-abi for smaller APK sizes.
• Consider flutter run --profile for performance testing instead of release mode.

Conclusion

You don’t have to put up with those slow build times. You can stand to save some time with optimizations like these, and the less time you spend waiting to code, the better. Begin with the low-hanging fruit – like turning on parallel Gradle execution – and move up.

Want to supercharge your Flutter workflow? Share your results with your team and TRY these tips TODAY!