Severe hang when rendering a short markdown string with 6-level nested bullet points

[hsinlei]

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Describe the bug Severe hang (1-2s) when rendering a relatively short markdown string (~hundreds of characters) with nested bullet points (6 levels).

Checklist

• [x] I can reproduce this issue with a vanilla SwiftUI project.
• [x] I can reproduce this issue using the main branch of this package.
• [x] This bug hasn't been addressed in an existing GitHub issue.

Steps to reproduce Explanation of how to reproduce the incorrect behavior. This could include an attached project, a link to code, or a Markdown-formatted text exhibiting the issue.

1. Clone this minimal demo project
2. Build and run it, tap the "Go" navigation link, and observe a 1-2s UI freezing before the view transition
3. Profile and record the run using XCode Instruments Timing Profiling tool, tap the "Go" navigation link, and observe "Severe Hang" and 100% CPU usage

Expected behavior Ideally no hang from rendering such a short markdown string. If heavy computation can't be easily optimized out, move the computation off of the main UI thread to avoid hangs.

Screenshots

Version information

• MarkdownUI: 2.3.0
• OS: iOS 17.4.1
• Xcode: 15.2

Additional context

• Looks like it has to do with the deeply nested bullet points (i.e. 6 levels)
• Un-nesting the deepest level of bullets (i.e. moving them to become siblings of their original parent bullets) mitigates the Severe Hang into just Hang
• Further un-nesting (i.e. reducing from 5 levels to 4 levels nested bullets) results in no Hang at all

[gonzalezreal]

Thanks for reporting. I will take a look as soon as I have some spare time.