Optimize hot paths for ~10% performance improvement

- Use \G regex anchor in parseSymbol/parseFootnoteRef to avoid
  redundant strpos() validation (match anchored at offset)
- Replace uksort() with array manipulation for attribute ordering
  in HtmlRenderer (faster id-first sorting)
- Add first-char switch in startsNewBlockSignificant() to avoid
  running 6 regex patterns on every line check

Benchmark (medium 56KB document):
- Before: 20.68 ms
- After: 18.44 ms (~11% faster)

Author: dereuromark

src/Parser/BlockParser.php

@@ -2470,8 +2470,14 @@ protected function appendToLastParagraph(Node $parent, string $content, int $lin
 
     protected function startsNewBlock(string $line): bool
     {
+        // Quick check: empty lines don't start blocks
+        if ($line === '' || !isset($line[0])) {
+            return false;
+        }
+
         // Caption `^ text` can always interrupt paragraphs (special case for figure captions)
-        if (preg_match('/^\^ /', $line)) {
+        // Quick first-char check before regex
+        if ($line[0] === '^' && isset($line[1]) && $line[1] === ' ') {
             return true;
         }
 
@@ -2497,37 +2503,43 @@ protected function startsNewBlock(string $line): bool
      */
     protected function startsNewBlockSignificant(string $line): bool
     {
-        // Headings, unordered lists, tables (same as standard)
-        if (preg_match('/^(#{1,6}\s|[-*+]\s|\|)/', $line)) {
-            return true;
-        }
-
-        // Block quotes
-        if (preg_match('/^>\s?/', $line)) {
-            return true;
-        }
-
-        // Ordered lists (digit or letter followed by . or ))
-        if (preg_match('/^(\d+|[a-zA-Z])[.)]\s/', $line)) {
-            return true;
-        }
-
-        // Code fences (with or without info string)
-        if (preg_match('/^`{3,}/', $line)) {
-            return true;
-        }
+        // Use first-char switch to avoid unnecessary regex checks
+        $first = $line[0];
+
+        switch ($first) {
+            case '#':
+                // Headings: #{1,6}\s
+                return preg_match('/^#{1,6}\s/', $line) === 1;
+            case '-':
+            case '*':
+            case '+':
+                // Unordered lists or thematic breaks
+                if (isset($line[1]) && $line[1] === ' ') {
+                    return true; // Unordered list
+                }
 
-        // Fenced divs
-        if (preg_match('/^:{3,}/', $line)) {
-            return true;
-        }
+                // Thematic breaks: *\s*\*\s*\* or -\s*-\s*-
+                return preg_match('/^(\*\s*\*\s*\*|-\s*-\s*-)/', $line) === 1;
+            case '|':
+                // Tables
+                return true;
+            case '>':
+                // Block quotes
+                return true;
+            case '`':
+                // Code fences: `{3,}
+                return isset($line[1], $line[2]) && $line[1] === '`' && $line[2] === '`';
+            case ':':
+                // Fenced divs: :{3,}
+                return isset($line[1], $line[2]) && $line[1] === ':' && $line[2] === ':';
+            default:
+                // Ordered lists: digit or letter followed by . or )
+                if (ctype_digit($first) || ctype_alpha($first)) {
+                    return preg_match('/^(\d+|[a-zA-Z])[.)]\s/', $line) === 1;
+                }
 
-        // Thematic breaks
-        if (preg_match('/^(\*\s*\*\s*\*|\-\s*\-\s*\-)/', $line)) {
-            return true;
+                return false;
         }
-
-        return false;
     }
 
     /**

src/Parser/InlineParser.php

@@ -1564,12 +1564,8 @@ protected function applyAttributesToNode(Node $node, string $attrStr): void
      */
     protected function parseFootnoteRef(string $text, int $pos): ?array
     {
-        // Match [^label]
-        if (!preg_match('/\[\^([^\]]+)\]/', $text, $matches, 0, $pos)) {
-            return null;
-        }
-
-        if (strpos($text, $matches[0], $pos) !== $pos) {
+        // Match [^label] - \G anchors at offset position, avoiding extra strpos check
+        if (!preg_match('/\G\[\^([^\]]+)\]/', $text, $matches, 0, $pos)) {
             return null;
         }
 
@@ -1645,12 +1641,8 @@ protected function parseMath(string $text, int $pos): ?array
      */
     protected function parseSymbol(string $text, int $pos): ?array
     {
-        // Match :word:
-        if (!preg_match('/:([a-zA-Z_][a-zA-Z0-9_-]*):/', $text, $matches, 0, $pos)) {
-            return null;
-        }
-
-        if (strpos($text, $matches[0], $pos) !== $pos) {
+        // Match :word: - \G anchors at offset position, avoiding extra strpos check
+        if (!preg_match('/\G:([a-zA-Z_][a-zA-Z0-9_-]*):/', $text, $matches, 0, $pos)) {
             return null;
         }
 

src/Renderer/HtmlRenderer.php

@@ -399,17 +399,12 @@ protected function renderAttributesExcluding(Node $node, array $exclude): string
             $attrs = $this->safeMode->filterAttributes($attrs);
         }
 
-        // Sort attributes: id first, then others in source order
-        uksort($attrs, function (string $a, string $b): int {
-            if ($a === 'id') {
-                return -1;
-            }
-            if ($b === 'id') {
-                return 1;
-            }
-
-            return 0;
-        });
+        // Put id first if present (faster than uksort)
+        if (isset($attrs['id'])) {
+            $id = $attrs['id'];
+            unset($attrs['id']);
+            $attrs = ['id' => $id] + $attrs;
+        }
 
         $html = '';
         foreach ($attrs as $key => $value) {
@@ -835,17 +830,12 @@ protected function renderAttributes(Node $node): string
             $attrs = $this->safeMode->filterAttributes($attrs);
         }
 
-        // Sort attributes: id first, then others in source order
-        uksort($attrs, function (string $a, string $b): int {
-            if ($a === 'id') {
-                return -1;
-            }
-            if ($b === 'id') {
-                return 1;
-            }
-
-            return 0; // preserve order for other attributes
-        });
+        // Put id first if present (faster than uksort)
+        if (isset($attrs['id'])) {
+            $id = $attrs['id'];
+            unset($attrs['id']);
+            $attrs = ['id' => $id] + $attrs;
+        }
 
         $html = '';
         foreach ($attrs as $key => $value) {