diff --git a/.changeset/tall-kids-juggle.md b/.changeset/tall-kids-juggle.md
new file mode 100644
index 0000000000..48a54b3436
--- /dev/null
+++ b/.changeset/tall-kids-juggle.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+perf: speed up parser a little bit
diff --git a/packages/svelte/src/compiler/phases/1-parse/index.js b/packages/svelte/src/compiler/phases/1-parse/index.js
index fa7b292640..8edd403487 100644
--- a/packages/svelte/src/compiler/phases/1-parse/index.js
+++ b/packages/svelte/src/compiler/phases/1-parse/index.js
@@ -10,25 +10,7 @@ import read_options from './read/options.js';
 import { is_reserved } from '../../../utils.js';
 import { disallow_children } from '../2-analyze/visitors/shared/special-element.js';
 import * as state from '../../state.js';
-
-/** @param {number} cc */
-function is_whitespace(cc) {
-	// fast path for common whitespace
-	if (cc === 32 || (cc <= 13 && cc >= 9)) return true;
-	// rare whitespace — \u00a0, \u1680, \u2000-\u200a, \u2028, \u2029, \u202f, \u205f, \u3000, \ufeff
-	if (cc < 160) return false;
-	return (
-		cc === 160 ||
-		cc === 5760 ||
-		(cc >= 8192 && cc <= 8202) ||
-		cc === 8232 ||
-		cc === 8233 ||
-		cc === 8239 ||
-		cc === 8287 ||
-		cc === 12288 ||
-		cc === 65279
-	);
-}
+import { is_whitespace } from './utils/whitespace.js';
 
 const regex_lang_attribute =
 	/<!--[^]*?-->|<script\s+(?:[^>]*|(?:[^=>'"/]+=(?:"[^"]*"|'[^']*'|[^>\s]+)\s+)*)lang=(["'])?([^"' >]+)\1[^>]*>/g;
@@ -278,8 +260,27 @@ export class Parser {
 		};
 	}
 
+	/** @param {string} delimiter */
+	read_until(delimiter) {
+		if (this.index >= this.template.length) {
+			if (this.loose) return '';
+			e.unexpected_eof(this.template.length);
+		}
+
+		const start = this.index;
+		const index = this.template.indexOf(delimiter, start);
+
+		if (index !== -1) {
+			this.index = index;
+			return this.template.slice(start, this.index);
+		}
+
+		this.index = this.template.length;
+		return this.template.slice(start);
+	}
+
 	/** @param {RegExp} pattern */
-	read_until(pattern) {
+	read_until_regex(pattern) {
 		if (this.index >= this.template.length) {
 			if (this.loose) return '';
 			e.unexpected_eof(this.template.length);
@@ -302,6 +303,7 @@ export class Parser {
 			e.expected_whitespace(this.index);
 		}
 
+		this.index++;
 		this.allow_whitespace();
 	}
 
diff --git a/packages/svelte/src/compiler/phases/1-parse/read/script.js b/packages/svelte/src/compiler/phases/1-parse/read/script.js
index 4472ce61c3..48fb540f9c 100644
--- a/packages/svelte/src/compiler/phases/1-parse/read/script.js
+++ b/packages/svelte/src/compiler/phases/1-parse/read/script.js
@@ -22,7 +22,7 @@ const ALLOWED_ATTRIBUTES = ['context', 'generics', 'lang', 'module'];
  */
 export function read_script(parser, start, attributes) {
 	const script_start = parser.index;
-	const data = parser.read_until(regex_closing_script_tag);
+	const data = parser.read_until_regex(regex_closing_script_tag);
 	if (parser.index >= parser.template.length) {
 		e.element_unclosed(parser.template.length, 'script');
 	}
diff --git a/packages/svelte/src/compiler/phases/1-parse/read/style.js b/packages/svelte/src/compiler/phases/1-parse/read/style.js
index df036d0d33..574c353adb 100644
--- a/packages/svelte/src/compiler/phases/1-parse/read/style.js
+++ b/packages/svelte/src/compiler/phases/1-parse/read/style.js
@@ -16,8 +16,6 @@ const REGEX_WHITESPACE_OR_COLON = /[\s:]/;
 const REGEX_LEADING_HYPHEN_OR_DIGIT = /-?\d/y;
 const REGEX_VALID_IDENTIFIER_CHAR = /[a-zA-Z0-9_-]/;
 const REGEX_UNICODE_SEQUENCE = /\\[0-9a-fA-F]{1,6}(\r\n|\s)?/y;
-const REGEX_COMMENT_CLOSE = /\*\//;
-const REGEX_HTML_COMMENT_CLOSE = /-->/;
 
 /**
  * @param {Parser} parser
@@ -478,7 +476,7 @@ function read_block_item(parser) {
 function read_declaration(parser) {
 	const start = parser.index;
 
-	const property = parser.read_until(REGEX_WHITESPACE_OR_COLON);
+	const property = parser.read_until_regex(REGEX_WHITESPACE_OR_COLON);
 	parser.allow_whitespace();
 	parser.eat(':');
 	let index = parser.index;
@@ -661,7 +659,7 @@ function allow_comment_or_whitespace(parser, capture_comments = true) {
 		}
 
 		if (parser.eat('<!--')) {
-			parser.read_until(REGEX_HTML_COMMENT_CLOSE);
+			parser.read_until('-->');
 			parser.eat('-->', true);
 		}
 
@@ -676,7 +674,7 @@ function allow_comment_or_whitespace(parser, capture_comments = true) {
 function read_comment(parser) {
 	const start = parser.index;
 	parser.eat('/*', true);
-	const value = parser.read_until(REGEX_COMMENT_CLOSE);
+	const value = parser.read_until('*/');
 	parser.eat('*/', true);
 	const end = parser.index;
 
diff --git a/packages/svelte/src/compiler/phases/1-parse/state/element.js b/packages/svelte/src/compiler/phases/1-parse/state/element.js
index a14dd167a5..220fe24b9d 100644
--- a/packages/svelte/src/compiler/phases/1-parse/state/element.js
+++ b/packages/svelte/src/compiler/phases/1-parse/state/element.js
@@ -15,13 +15,10 @@ import { get_attribute_expression, is_expression_attribute } from '../../../util
 import { closing_tag_omitted } from '../../../../html-tree-validation.js';
 import { list } from '../../../utils/string.js';
 import { locator } from '../../../state.js';
-import * as b from '#compiler/builders';
+import { is_whitespace } from '../utils/whitespace.js';
 
 const regex_invalid_unquoted_attribute_value = /(\/>|[\s"'=<>`])/y;
 const regex_closing_textarea_tag = /<\/textarea(\s[^>]*)?>/iy;
-const regex_closing_comment = /-->/;
-const regex_whitespace_or_slash_or_closing_tag = /(\s|\/|>)/;
-const regex_token_ending_character = /[\s=/>"']/;
 const regex_starts_with_quote_characters = /["']/y;
 const regex_attribute_value = /(?:"([^"]*)"|'([^'])*'|([^>\s]+))/y;
 const regex_doctype_name = /^![a-zA-Z]+$/;
@@ -67,7 +64,7 @@ export default function element(parser) {
 	let parent = parser.current();
 
 	if (parser.eat('!--')) {
-		const data = parser.read_until(regex_closing_comment);
+		const data = parser.read_until('-->');
 		parser.eat('-->', true);
 
 		parser.append({
@@ -81,7 +78,7 @@ export default function element(parser) {
 	}
 
 	if (parser.eat('/')) {
-		const name = parser.read_until(regex_whitespace_or_slash_or_closing_tag);
+		const name = read_tag_name(parser);
 
 		parser.allow_whitespace();
 		parser.eat('>', true);
@@ -137,7 +134,7 @@ export default function element(parser) {
 		return;
 	}
 
-	const tag = read_tag(parser, regex_whitespace_or_slash_or_closing_tag);
+	const tag = read_tag(parser);
 
 	if (tag.name.startsWith('svelte:') && !meta_tags.has(tag.name)) {
 		const bounds = { start: start + 1, end: start + 1 + tag.name.length };
@@ -475,7 +472,7 @@ function parent_is_shadowroot_template(stack) {
 function read_static_attribute(parser) {
 	const start = parser.index;
 
-	const tag = read_tag(parser, regex_token_ending_character);
+	const tag = read_tag(parser, true);
 	if (!tag.name) return null;
 
 	/** @type {true | Array<AST.Text | AST.ExpressionTag>} */
@@ -607,7 +604,7 @@ function read_attribute(parser) {
 		}
 	}
 
-	const tag = read_tag(parser, regex_token_ending_character);
+	const tag = read_tag(parser, true);
 
 	if (!tag.name) return null;
 
@@ -731,7 +728,7 @@ function read_comment(parser) {
 	const start = parser.index;
 
 	if (parser.eat('//')) {
-		const value = parser.read_until(/\n/);
+		const value = parser.read_until('\n');
 		const end = parser.index;
 
 		return {
@@ -747,7 +744,7 @@ function read_comment(parser) {
 	}
 
 	if (parser.eat('/*')) {
-		const value = parser.read_until(/\*\//);
+		const value = parser.read_until('*/');
 
 		parser.eat('*/');
 		const end = parser.index;
@@ -847,25 +844,21 @@ function read_attribute_value(parser) {
  * @returns {any[]}
  */
 function read_sequence(parser, done, location) {
-	/** @type {AST.Text} */
-	let current_chunk = {
-		start: parser.index,
-		end: -1,
-		type: 'Text',
-		raw: '',
-		data: ''
-	};
-
 	/** @type {Array<AST.Text | AST.ExpressionTag>} */
 	const chunks = [];
+	let chunk_start = parser.index;
 
 	/** @param {number} end */
 	function flush(end) {
-		if (end > current_chunk.start) {
-			current_chunk.raw = parser.template.slice(current_chunk.start, end);
-			current_chunk.data = decode_character_references(current_chunk.raw, true);
-			current_chunk.end = end;
-			chunks.push(current_chunk);
+		if (end > chunk_start) {
+			const raw = parser.template.slice(chunk_start, end);
+			chunks.push({
+				start: chunk_start,
+				end,
+				type: 'Text',
+				raw,
+				data: decode_character_references(raw, true)
+			});
 		}
 	}
 
@@ -879,12 +872,14 @@ function read_sequence(parser, done, location) {
 			if (parser.match('#')) {
 				const index = parser.index - 1;
 				parser.eat('#');
-				const name = parser.read_until(/[^a-z]/);
+				// const name = parser.read_until_regex(/[^a-z]/);
+				const name = read_lowercase_name(parser);
 				e.block_invalid_placement(index, name, location);
 			} else if (parser.match('@')) {
 				const index = parser.index - 1;
 				parser.eat('@');
-				const name = parser.read_until(/[^a-z]/);
+				// const name = parser.read_until_regex(/[^a-z]/);
+				const name = read_lowercase_name(parser);
 				e.tag_invalid_placement(index, name, location);
 			}
 
@@ -907,14 +902,7 @@ function read_sequence(parser, done, location) {
 			};
 
 			chunks.push(chunk);
-
-			current_chunk = {
-				start: parser.index,
-				end: -1,
-				type: 'Text',
-				raw: '',
-				data: ''
-			};
+			chunk_start = parser.index;
 		} else {
 			parser.index++;
 		}
@@ -929,12 +917,36 @@ function read_sequence(parser, done, location) {
 
 /**
  * @param {Parser} parser
- * @param {RegExp} regex
+ * @param {boolean} [attribute]
+ */
+function read_tag_name(parser, attribute = false) {
+	const start = parser.index;
+	if (start >= parser.template.length && !parser.loose) e.unexpected_eof(parser.template.length);
+
+	while (parser.index < parser.template.length) {
+		const cc = parser.template.charCodeAt(parser.index);
+		if (
+			is_whitespace(cc) ||
+			cc === 47 || // /
+			cc === 62 || // >
+			(attribute && (cc === 34 || cc === 39 || cc === 61)) // " ' =
+		) {
+			break;
+		}
+		parser.index += 1;
+	}
+
+	return parser.template.slice(start, parser.index);
+}
+
+/**
+ * @param {Parser} parser
+ * @param {boolean} [attribute]
  * @returns {Identifier & { start: number, end: number, loc: SourceLocation }}
  */
-function read_tag(parser, regex) {
+function read_tag(parser, attribute = false) {
 	const start = parser.index;
-	const name = parser.read_until(regex);
+	const name = read_tag_name(parser, attribute);
 	const end = parser.index;
 
 	return {
@@ -948,3 +960,15 @@ function read_tag(parser, regex) {
 		}
 	};
 }
+
+/** @param {Parser} parser */
+function read_lowercase_name(parser) {
+	const start = parser.index;
+	while (parser.index < parser.template.length) {
+		const cc = parser.template.charCodeAt(parser.index);
+		// a-z
+		if (cc < 97 || cc > 122) break;
+		parser.index += 1;
+	}
+	return parser.template.slice(start, parser.index);
+}
diff --git a/packages/svelte/src/compiler/phases/1-parse/utils/html.js b/packages/svelte/src/compiler/phases/1-parse/utils/html.js
index ccb2005054..dd0b0224a6 100644
--- a/packages/svelte/src/compiler/phases/1-parse/utils/html.js
+++ b/packages/svelte/src/compiler/phases/1-parse/utils/html.js
@@ -38,6 +38,8 @@ const entity_pattern_attr_value = get_entity_pattern(true);
  * @param {boolean} is_attribute_value
  */
 export function decode_character_references(html, is_attribute_value) {
+	if (html.indexOf('&') === -1) return html; // fast path
+
 	const entity_pattern = is_attribute_value ? entity_pattern_attr_value : entity_pattern_content;
 	return html.replace(
 		entity_pattern,
diff --git a/packages/svelte/src/compiler/phases/1-parse/utils/whitespace.js b/packages/svelte/src/compiler/phases/1-parse/utils/whitespace.js
new file mode 100644
index 0000000000..b9a7efc9a3
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/1-parse/utils/whitespace.js
@@ -0,0 +1,18 @@
+/** @param {number} cc */
+export function is_whitespace(cc) {
+	// fast path for common whitespace
+	if (cc === 32 || (cc <= 13 && cc >= 9)) return true;
+	// rare whitespace — \u00a0, \u1680, \u2000-\u200a, \u2028, \u2029, \u202f, \u205f, \u3000, \ufeff
+	if (cc < 160) return false;
+	return (
+		cc === 160 ||
+		cc === 5760 ||
+		(cc >= 8192 && cc <= 8202) ||
+		cc === 8232 ||
+		cc === 8233 ||
+		cc === 8239 ||
+		cc === 8287 ||
+		cc === 12288 ||
+		cc === 65279
+	);
+}
diff --git a/packages/svelte/src/compiler/state.js b/packages/svelte/src/compiler/state.js
index 5ae001ec50..51a02a61e1 100644
--- a/packages/svelte/src/compiler/state.js
+++ b/packages/svelte/src/compiler/state.js
@@ -33,10 +33,14 @@ export let component_name = '<unknown>';
 export let source;
 
 /**
- * The source code split into lines (set by `set_source`)
- * @type {string[]}
+ * The source code split into lines, initialized when a diagnostic needs a code frame
+ * @type {string[] | undefined}
  */
-export let source_lines = [];
+let source_lines;
+
+export function get_source_lines() {
+	return (source_lines ??= source.split('\n'));
+}
 
 /**
  * True if compiling with `dev: true`
@@ -52,7 +56,7 @@ export let locator;
 /** @param {string} value */
 export function set_source(value) {
 	source = value;
-	source_lines = source.split('\n');
+	source_lines = undefined;
 
 	const l = getLocator(source, { offsetLine: 1 });
 
@@ -141,7 +145,7 @@ export function reset(state) {
 	runes = false;
 	component_name = UNKNOWN_FILENAME;
 	source = '';
-	source_lines = [];
+	source_lines = undefined;
 	filename = (state.filename ?? UNKNOWN_FILENAME).replace(/\\/g, '/');
 	warning_filter = state.warning ?? (() => true);
 	warnings = [];
diff --git a/packages/svelte/src/compiler/utils/compile_diagnostic.js b/packages/svelte/src/compiler/utils/compile_diagnostic.js
index 95d028ee35..ab0732c958 100644
--- a/packages/svelte/src/compiler/utils/compile_diagnostic.js
+++ b/packages/svelte/src/compiler/utils/compile_diagnostic.js
@@ -15,7 +15,7 @@ function tabs_to_spaces(str) {
  * @param {number} column
  */
 function get_code_frame(line, column) {
-	const lines = state.source_lines;
+	const lines = state.get_source_lines();
 	const frame_start = Math.max(0, line - 2);
 	const frame_end = Math.min(line + 3, lines.length);
 	const digits = String(frame_end + 1).length;