diff --git a/_test_utils/perf_fixtures.ts b/_test_utils/perf_fixtures.ts
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+++ b/_test_utils/perf_fixtures.ts
@@ -0,0 +1,523 @@
+import type { WikitextEvent } from '../events.ts';
+
+import {
+  blockEvents,
+  buildTree,
+  createSession,
+  events,
+  inlineEvents,
+  outlineEvents,
+  parse,
+  tokenize,
+} from '../mod.ts';
+import { UNICODE_TEXT_FIXTURES } from './unicode_fixtures.ts';
+
+const CC_LF = 0x0a;
+const CC_CR = 0x0d;
+const CC_TAB = 0x09;
+const CC_SPACE = 0x20;
+const CC_BANG = 0x21;
+const CC_HASH = 0x23;
+const CC_AMP = 0x26;
+const CC_APOSTROPHE = 0x27;
+const CC_ASTERISK = 0x2a;
+const CC_DASH = 0x2d;
+const CC_SLASH = 0x2f;
+const CC_COLON = 0x3a;
+const CC_SEMICOLON = 0x3b;
+const CC_LT = 0x3c;
+const CC_EQUALS = 0x3d;
+const CC_GT = 0x3e;
+const CC_OPEN_BRACKET = 0x5b;
+const CC_CLOSE_BRACKET = 0x5d;
+const CC_UNDERSCORE = 0x5f;
+const CC_OPEN_BRACE = 0x7b;
+const CC_PIPE = 0x7c;
+const CC_CLOSE_BRACE = 0x7d;
+const CC_TILDE = 0x7e;
+
+export type RangeState = {
+  get(name: string): number;
+};
+
+export function repeatBlock(unit: string, repeat: number): string {
+  return unit.repeat(repeat);
+}
+
+export function repeatToMinimumSize(unit: string, minimum_size: number): string {
+  const repeat = Math.ceil(minimum_size / unit.length);
+  return unit.repeat(repeat);
+}
+
+export function cycleInputs<T>(inputs: readonly T[]): () => T {
+  let index = 0;
+
+  return () => {
+    const input = inputs[index];
+    index = (index + 1) % inputs.length;
+    return input;
+  };
+}
+
+const PLAIN_PARAGRAPH_UNITS = [
+  [
+    'Observational astronomy records atmospheric scattering, continental weathering, and navigational corrections across multiple expeditions.',
+    'Field notes preserve calibration details, seasonal drift, and cross-check remarks so later readers can reconstruct the original measurement context.',
+  ].join(' '),
+  [
+    'Archival restoration teams compare transcription variants, publication histories, and editorial interventions before they publish a stable reference text.',
+    'That workflow emphasizes provenance, reproducibility, and careful language around uncertainty instead of collapsing every disagreement into one canonical sentence.',
+  ].join(' '),
+  [
+    'Long-form technical prose often mixes descriptive paragraphs, cautious qualifications, and domain-specific terminology while still remaining ordinary text to the tokenizer.',
+    'This fixture aims to model that kind of paragraph payload rather than a short pangram repeated until the benchmark reaches its target size.',
+  ].join(' '),
+] as const;
+
+const PLAIN_WORD_BOUNDARY_STRESS_UNIT = [
+  'a a a a a a a a a a a a a a a a',
+  'b b b b b b b b b b b b b b b b',
+  'c c c c c c c c c c c c c c c c',
+].join(' ');
+
+export function repeatParagraphText(unit: string, minimum_size: number): string {
+  return repeatToMinimumSize(`${unit}\n\n`, minimum_size);
+}
+
+export function repeatWordBoundaryStressText(minimum_size: number): string {
+  return repeatToMinimumSize(`${PLAIN_WORD_BOUNDARY_STRESS_UNIT}\n`, minimum_size);
+}
+
+export const TOKENIZER_SCAN_DELIMITER = Uint8Array.from({ length: 128 }, (_, code) => {
+  switch (code) {
+    case CC_LF:
+    case CC_CR:
+    case CC_TAB:
+    case CC_SPACE:
+    case CC_BANG:
+    case CC_HASH:
+    case CC_AMP:
+    case CC_APOSTROPHE:
+    case CC_ASTERISK:
+    case CC_DASH:
+    case CC_SLASH:
+    case CC_COLON:
+    case CC_SEMICOLON:
+    case CC_LT:
+    case CC_EQUALS:
+    case CC_GT:
+    case CC_OPEN_BRACKET:
+    case CC_CLOSE_BRACKET:
+    case CC_UNDERSCORE:
+    case CC_OPEN_BRACE:
+    case CC_PIPE:
+    case CC_CLOSE_BRACE:
+    case CC_TILDE:
+      return 1;
+
+    default:
+      return 0;
+  }
+});
+
+export const PLAIN_TEXT_INPUTS = [
+  repeatParagraphText(PLAIN_PARAGRAPH_UNITS[0], 9 * 1024),
+  repeatParagraphText(PLAIN_PARAGRAPH_UNITS[1], 9 * 1024),
+  repeatParagraphText(PLAIN_PARAGRAPH_UNITS[2], 9 * 1024),
+] as const;
+
+export const PLAIN_TOKEN_DENSITY_STRESS_INPUTS = [
+  repeatWordBoundaryStressText(9 * 1024),
+  repeatToMinimumSize(`${PLAIN_WORD_BOUNDARY_STRESS_UNIT}\t${PLAIN_WORD_BOUNDARY_STRESS_UNIT}\n`, 9 * 1024),
+] as const;
+
+export const HEADING_TEXT_INPUTS = [
+  '== Section ==\nParagraph text here.\n'.repeat(100),
+  '=== Nested ===\nAnother paragraph line.\n'.repeat(90),
+] as const;
+
+export const TABLE_TEXT_INPUTS = [
+  '{|\n! H1 !! H2\n|-\n| A || B\n|-\n| C || D\n|}\n'.repeat(50),
+  '{| class="wikitable"\n! Name !! Value\n|-\n| Alpha || 1\n|-\n| Beta || 2\n|}\n'.repeat(40),
+] as const;
+
+export const LINK_TEXT_INPUTS = [
+  "See [[Main Page|home]], '''bold''' and ''italic'' text.\n".repeat(100),
+  'Visit [[Earth|planet]] with [https://example.com source] and &amp; notes.\n'.repeat(80),
+] as const;
+
+export const TEMPLATE_TEXT_INPUTS = [
+  '{{Infobox|name={{{1}}}|value={{{2|default}}}}}\n'.repeat(100),
+  '{{Card|title={{PAGENAME}}|body={{{content|fallback}}}}}\n'.repeat(85),
+] as const;
+
+export const MIXED_TEXT_INPUTS = [
+  [
+    '== Heading ==',
+    "'''Bold''' and ''italic'' and '''''both'''''.",
+    '* Bullet item',
+    '# Ordered item',
+    ': Indented',
+    '{|',
+    '! Header',
+    '|-',
+    '| [[Page|link]] || {{template|arg=val}}',
+    '|}',
+    '----',
+    '<!-- comment -->',
+    '&amp; &#123; &#x1F4A9;',
+    '~~~~ __TOC__',
+    '',
+  ].join('\n').repeat(50),
+  [
+    '== Another Heading ==',
+    "A [[Main Page|home]] link with ''italic'' and '''bold'''.",
+    '; Term',
+    ': Definition',
+    '{|',
+    '! Name !! Count',
+    '|-',
+    '| {{Item|name=Alpha}} || 42',
+    '|}',
+    '<span class="lead">inline</span>',
+    '&lt;escaped&gt; ~~ ~~ __TOC__',
+    '',
+  ].join('\n').repeat(48),
+] as const;
+
+export const PATHOLOGICAL_TEXT_INPUTS = [
+  [
+    '[[[[{{{{<!--',
+    '__BROKEN_',
+    '<ref name="n">',
+    "'''''",
+    '&broken',
+    '```md',
+    '{|',
+    '|-',
+    '| [[Page|{{T|x}}]] || <span class="x">text',
+    '',
+  ].join('\n').repeat(70),
+  [
+    '{{{{{{',
+    '[[File:Example.jpg|thumb|{{Card|name=[[Main Page|home]]}}]]',
+    '<nowiki>[[literal]] {{literal}}</nowiki>',
+    '<!-- unclosed comment opener',
+    '~~~~ __BROKEN_',
+    '|| !! | |}',
+    '',
+  ].join('\n').repeat(55),
+] as const;
+
+export const INLINE_HEAVY_TEXT_INPUTS = [
+  [
+    '== References ==',
+    "A [[Main Page|home]] link with ''italic'', '''bold''', and '''''both'''''.",
+    '<ref name="cite-1" group="note">Example &amp; entity</ref>',
+    '<span class="lead">inline tag</span> and <br/> break.',
+    '__TOC__ {{Infobox|name=value|title={{{1|Default}}}}}',
+    'A <nowiki>[[literal]] {{literal}}</nowiki> segment.',
+    '',
+  ].join('\n').repeat(80),
+  [
+    '== Inline ==',
+    '[[Main Page|home]] [https://example.com ref] {{Card|name=value|body=<span>ok</span>}}',
+    '<ref name="cite-2">\'\'quoted\'\' &amp; entity</ref>',
+    'A <nowiki>[[literal]]</nowiki> block with __TOC__ nearby.',
+    '',
+  ].join('\n').repeat(90),
+] as const;
+
+export const SAME_SIZE_PLAIN_TEXT = repeatParagraphText(
+  [
+    'Reference documentation for event-driven parsers usually spends more bytes on terminology, examples, and caveats than on symbolic punctuation.',
+    'That kind of paragraph prose is still plain text, but it has longer average word length and fewer extreme token boundaries per kilobyte than the old pangram fixture.',
+  ].join(' '),
+  8 * 1024,
+);
+
+export const SAME_SIZE_PLAIN_TOKEN_DENSITY_STRESS_TEXT = repeatWordBoundaryStressText(8 * 1024);
+
+export const SAME_SIZE_MIXED_TEXT = repeatBlock([
+  '== Heading ==',
+  "A [[Main Page|home]] link with ''italic'' and '''bold'''.",
+  '* Bullet item',
+  '{|',
+  '! Header !! Count',
+  '|-',
+  '| {{Item|name=Alpha}} || 42',
+  '|}',
+  '&amp; __TOC__',
+  '',
+].join('\n'), 24);
+
+export const SAME_SIZE_PATHOLOGICAL_TEXT = repeatBlock([
+  '[[[[{{{{<!--',
+  '__BROKEN_',
+  '<ref name="n">',
+  "'''''",
+  '&broken',
+  '```md',
+  '{|',
+  '| [[Page|{{T|x}}]] || <span class="x">text',
+  '',
+].join('\n'), 30);
+
+export type UnicodeBenchFixture = {
+  key: string;
+  label: string;
+  text_input: string;
+  document_input: string;
+};
+
+function createUnicodeBenchFixture(
+  fixture: (typeof UNICODE_TEXT_FIXTURES)[number],
+): UnicodeBenchFixture {
+  const text_input = repeatToMinimumSize(`${fixture.sample}`, 8 * 1024);
+  const document_unit = [
+    `== ${fixture.sample} ==`,
+    fixture.sample,
+    `* ${fixture.sample}`,
+    '',
+  ].join('\n');
+
+  return {
+    key: fixture.key,
+    label: fixture.label,
+    text_input,
+    document_input: repeatToMinimumSize(`${document_unit}\n`, 8 * 1024),
+  };
+}
+
+export const UNICODE_BENCH_FIXTURES = UNICODE_TEXT_FIXTURES.map(createUnicodeBenchFixture);
+
+export const SYNTHETIC_ARTICLE_INPUTS = [
+  repeatBlock([
+    '{{Infobox settlement|name=Example City|population_total=123456|map={{Location map|World}}}}',
+    '== Lead ==',
+    "Example City is a ''fictional'' place with [[Main Page|notable links]], references, and templates.",
+    '== History ==',
+    '* Founded in 1901',
+    '* Expanded with {{Convert|25|km|mi}} of rail',
+    '== Geography ==',
+    '{| class="wikitable"',
+    '! District !! Population',
+    '|-',
+    '| North || 42000',
+    '|-',
+    '| South || 38000',
+    '|}',
+    '== Culture ==',
+    '<ref name="cite-1">A cited note with &amp; entity</ref>',
+    '<span class="lead">Inline tag</span> with __TOC__ and <br/> break.',
+    '',
+  ].join('\n'), 48),
+  repeatBlock([
+    '{{Infobox person|name=Example Person|occupation=Writer|known_for=[[Sample work]]}}',
+    '== Summary ==',
+    "Example Person wrote about [[Earth|the world]], ''style'', and '''emphasis'''.",
+    '== Works ==',
+    '# First book',
+    '# Second book with {{Smallcaps|Title}}',
+    '== Notes ==',
+    '; Theme',
+    ': Mixed prose with [https://example.com source] and <ref group="note">footnote</ref>.',
+    '== Data ==',
+    '{| class="wikitable"',
+    '! Year !! Work',
+    '|-',
+    '| 2001 || [[Alpha]]',
+    '|-',
+    '| 2007 || [[Beta]]',
+    '|}',
+    '',
+  ].join('\n'), 52),
+] as const;
+
+export const LARGE_FILE_MINIMUM_SIZE = 100 * 1024 * 1024;
+
+const LARGE_STREAMING_ARTICLE_UNIT = [
+  '== Lead ==',
+  "A [[Main Page|home]] link with ''italic'', '''bold''', and {{Card|name=value|body={{Nested|x=1}}}}.",
+  '* Bullet item with [https://example.com source] and &amp; entity.',
+  '# Ordered item with <ref name="cite-1">inline reference text</ref>.',
+  '{| class="wikitable"',
+  '! Name !! Value',
+  '|-',
+  '| Alpha || [[Page|Display]]',
+  '|-',
+  '| Beta || {{Template|arg=value|body=<span class="x">inline</span>}}',
+  '|}',
+  '<nowiki>[[literal]] {{literal}}</nowiki>',
+  '__TOC__ ~~~~',
+  '',
+].join('\n');
+
+export const LARGE_STREAMING_ARTICLE_TEXT = repeatToMinimumSize(
+  `${LARGE_STREAMING_ARTICLE_UNIT}\n`,
+  LARGE_FILE_MINIMUM_SIZE,
+);
+
+export function drainTokenize(input: string): number {
+  let count = 0;
+  for (const _tok of tokenize(input)) {
+    count++;
+  }
+  return count;
+}
+
+export function drainTokenizerScanOnly(input: string): number {
+  let checksum = 0;
+
+  for (let index = 0; index < input.length; index++) {
+    const code = input.charCodeAt(index);
+    checksum += code;
+
+    if (code < 128 && TOKENIZER_SCAN_DELIMITER[code]) {
+      checksum ^= index;
+    }
+  }
+
+  return checksum;
+}
+
+export function formatTokenCount(count: number): string {
+  if (count >= 1000) {
+    return `${(count / 1000).toFixed(1)}K`;
+  }
+
+  return `${count}`;
+}
+
+export function countTokenizerDelimiters(input: string): number {
+  let count = 0;
+
+  for (let index = 0; index < input.length; index++) {
+    const code = input.charCodeAt(index);
+    if (code < 128 && TOKENIZER_SCAN_DELIMITER[code]) {
+      count++;
+    }
+  }
+
+  return count;
+}
+
+export function describeTokenizeFixture(name: string, input: string): string {
+  const token_count = drainTokenize(input);
+  const emitted_tokens = Math.max(token_count - 1, 0);
+  const chars_per_token = emitted_tokens === 0
+    ? '0.00'
+    : (input.length / emitted_tokens).toFixed(2);
+  const delimiter_count = countTokenizerDelimiters(input);
+  const delimiters_per_kb = ((delimiter_count * 1024) / input.length).toFixed(1);
+
+  return `${name}, ${formatTokenCount(emitted_tokens)} tokens, ${chars_per_token} chars/token, ${delimiters_per_kb} delimiters/KB`;
+}
+
+export function drainBlockEvents(input: string): number {
+  let count = 0;
+  for (const _event of blockEvents(input, tokenize(input))) {
+    count++;
+  }
+  return count;
+}
+
+export function drainInlineEvents(input: string): number {
+  let count = 0;
+  for (const _event of inlineEvents(input, blockEvents(input, tokenize(input)))) {
+    count++;
+  }
+  return count;
+}
+
+export type TreeBuildFixture = {
+  source: string;
+  events: WikitextEvent[];
+};
+
+export type OutlineTreeBuildFixture = {
+  source: string;
+  events: WikitextEvent[];
+};
+
+export function createTreeBuildFixture(source: string): TreeBuildFixture {
+  return {
+    source,
+    events: Array.from(inlineEvents(source, blockEvents(source, tokenize(source)))),
+  };
+}
+
+export function createOutlineTreeBuildFixture(source: string): OutlineTreeBuildFixture {
+  return {
+    source,
+    events: Array.from(outlineEvents(source)),
+  };
+}
+
+export function drainBuildTreeFromEvents(fixture: TreeBuildFixture): number {
+  const tree = buildTree(fixture.events, { source: fixture.source });
+  return tree.children.length;
+}
+
+export function drainBuildTreeFromOutline(fixture: OutlineTreeBuildFixture): number {
+  const tree = buildTree(fixture.events, { source: fixture.source });
+  return tree.children.length;
+}
+
+export function drainStatelessLayeredWorkflow(source: string): number {
+  const outline_count = Array.from(outlineEvents(source)).length;
+  const full_event_count = Array.from(events(source)).length;
+  const tree_child_count = parse(source).children.length;
+
+  return outline_count + full_event_count + tree_child_count;
+}
+
+export function drainSessionLayeredWorkflowCold(source: string): number {
+  const session = createSession(source);
+  const outline_count = Array.from(session.outline()).length;
+  const full_event_count = Array.from(session.events()).length;
+  const tree_child_count = session.parse().children.length;
+
+  return outline_count + full_event_count + tree_child_count;
+}
+
+export function drainSessionLayeredWorkflowWarm(source: string): number {
+  const session = createSession(source);
+  Array.from(session.outline());
+  Array.from(session.events());
+  session.parse();
+
+  const outline_count = Array.from(session.outline()).length;
+  const full_event_count = Array.from(session.events()).length;
+  const tree_child_count = session.parse().children.length;
+
+  return outline_count + full_event_count + tree_child_count;
+}
+
+export function drainSessionOutlineWarm(source: string): number {
+  const session = createSession(source);
+  Array.from(session.outline());
+
+  let count = 0;
+  for (const _event of session.outline()) {
+    count++;
+  }
+  return count;
+}
+
+export function drainSessionEventsWarm(source: string): number {
+  const session = createSession(source);
+  Array.from(session.events());
+
+  let count = 0;
+  for (const _event of session.events()) {
+    count++;
+  }
+  return count;
+}
+
+export function drainSessionParseWarm(source: string): number {
+  const session = createSession(source);
+  session.parse();
+  return session.parse().children.length;
+}
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