Describe the bug

When using Svelte 5.25.6, a simple SVG drawing app (adapted from this Joy of Code example) seems to create a memory leak.

Screenshot shows a snapshot of the heap using Chrome dev tools. Notice the instances of Circle that have accumulated, despite the canvas being cleared.

The same example works fine in Svelte 5.19.6 (not tested any other versions).

Initially posted on StackOverflow.

Reproduction

Run the example from the links below, hit "Add 2 Circles" once and "Delete Circle" twice. The canvas is clear, but inspecting the heap using Chrome shows instances of Circle class still retained.

Repeat several times and the retained instances accumulate.

Perform the same experiment on 5.19.6 and once the canvas is clear, no instances of Circle are retained.

https://svelte.dev/playground/9aa0409c6b4f4e2bba5939553ab2d6d0?version=5.25.6 (memory leak)
https://svelte.dev/playground/9aa0409c6b4f4e2bba5939553ab2d6d0?version=5.19.6 (no memory leak)

Logs

System Info

npx envinfo --system --npmPackages svelte,rollup,webpack --binaries --browsers

  System:
    OS: macOS 15.1.1
    CPU: (8) arm64 Apple M1 Pro
    Memory: 149.80 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.9.0 - ~/.nvm/versions/node/v20.9.0/bin/node
    Yarn: 1.22.19 - /opt/homebrew/bin/yarn
    npm: 10.1.0 - ~/.nvm/versions/node/v20.9.0/bin/npm
    pnpm: 9.2.0 - ~/Library/pnpm/pnpm
  Browsers:
    Chrome: 135.0.7049.41
    Safari: 18.1.1
  npmPackages:
    svelte: ^5.0.0 => 5.25.6

Severity

blocking an upgrade