DartPad should add repaint boundaries around animated widgets.

[davidhicks980]

What happened?

DartPad has visual stutters, especially on lower-end devices.

Steps to reproduce problem

Press any inkwell.

Additional info

I profiled and the whole app appears to be repainting on small widget repaints. See here:

Screen.Recording.2025-01-13.at.4.31.57.PM.mov

Without repaint boundary around button (each paint repaints the entire widget tree):

Screen.Recording.2025-01-13.at.5.48.32.PM.mov

With repaint boundary (first paint repaints entire widget tree. Subsequent paints don't. Note the length of the frame).

Screen.Recording.2025-01-13.at.5.47.47.PM.mov

Browser

Browser: Chrome 131.0.6778.265 arm64

Version:

Are you using any extensions/plugins that affect website behavior
(particularly those that affect iframes, such as ad blockers)?

Are there any warnings or errors in your browser's JavaScript console?
If so, paste them below:

N/A

Machine

Operating system: M1 Pro MacOS

Version:

Your code

What code was in the editor, if any, when the failure occurred? You
can paste it in below:

N/A

DartPad's output

Did DartPad print anything to the console pane? If so, paste it below:

N/A

If you were running Flutter code, you can also paste an image of the
Flutter output directly into this bug report.

[johnpryan]

Thanks for filing an issue, for this type of thing, we recommend using DevTool's Highlight Repaints feature on an app running using a local version of Flutter.

[devoncarew]

@davidhicks980 - was your issue more about performance issues with the dartpad codebase itself?

[davidhicks980]

@devoncarew Yeah, but it is somewhat minor so I was going to let it close. I pulled the codebase and was trying to figure out why it felt a bit janky on web. Everything appeared to work fine, but the whole app painting on small changes was leading to some jank. Not sure how helpful the issue is -- I know repaint boundaries also add some overhead by inserting new layers -- but I wanted to let you all know.

[johnpryan]

Sorry, I misunderstood the issue. We should make sure we're efficiently rebuilding widgets, thanks for digging in.