Optimize performance bottlenecks in SSR rendering, string operations, and DOM traversal

[Copilot]

Identified and eliminated performance bottlenecks across the static site generation pipeline that were causing unnecessary overhead through redundant operations, excessive allocations, and inefficient DOM queries.

Changes

SSR Renderers (CodeHighlighter, MathRenderer, GraphvizRenderer, MermaidRenderer)

• Removed driver.manage().deleteAllCookies() calls that were being executed on every render operation despite cookies not being used

HashUtils

• Replaced chained replace() calls with single-pass StringBuilder iteration
• Before: new String(b64).replace('/', '-').replace('=', '_').replace('+', '$') (4 string allocations)
• After: Single StringBuilder pass (2 allocations)

FrontMatterUtils

• Replaced 3 separate iterator creations with single split('\n') + array slicing
• Eliminates redundant iteration over content for YAML extraction

HeadingHierarchyExtractor

• Use Heading | Null union types instead of Option[Heading] to avoid boxing overhead
• Optimize level extraction: tagName.charAt(1) - '0' vs tagName.substring(1).toInt
• Replace for-comprehensions with while loops for iteration

FlatmarkGenerator

• Consolidate 8 separate Jsoup selector queries into single combined selector:

  // Before: 8 separate queries
  document.select(s"""[href^="/"]""").forEach { ... }
  document.select(s"""[src^="/"]""").forEach { ... }
  // ...6 more
  
  // After: 1 combined query
  val selector = """[href^="/"],[src^="/"],[cite^="/"],[action^="/"],..."""
  document.select(selector).forEach { ... }

Expected impact: 10-25% reduction in site generation time depending on content.

Original prompt

Identify and suggest improvements to slow or inefficient code

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