Boosting Flutter Image Processing Performance with Rust ~40x speed up

I recently faced a task in Flutter: combine multiple high-resolution images (taken by mobile phones) vertically. While this sounds simple, the performance was a big issue.

The Challenge

I used a Pixel 8 Pro to combine three 3024×4032 images.

1. Dart (main thread):

• ❌ UI froze for 17 seconds.
• App Size: 27.9MB (Apk)

2. Dart (Isolate):

• ✅ UI stayed smooth.
• But it took 42 seconds — still way too slow!
• App Size: 27.9MB (Apk)

At this point, I knew I had to find another way, d art is not ideal for high-performance tasks. Its single-threaded design means that even using isolates won’t achieve the efficiency of true multithreading, especially for demanding tasks like image processing.

Solution: Rust 🦀

I decided to try Rust to handle the image processing logic.

Boom! Processing time dropped to just 1 second.

Here’s the breakdown:

• Dart (main thread): 17,667 ms (17 seconds), App Size: 27.9MB (Apk)
• Dart (Isolate): 42,840 ms (42 seconds), App…