early check for strong first matches, helps with https://github.com/microsoft/vscode/issues/91807

src/vs/base/common/filters.ts

@@ -559,6 +559,8 @@ export function fuzzyScore(pattern: string, patternLow: string, patternStart: nu
 	let patternPos = patternStart;
 	let wordPos = wordStart;
 
+	let hasStrongFirstMatch = false;
+
 	// There will be a match, fill in tables
 	for (row = 1, patternPos = patternStart; patternPos < patternLen; row++, patternPos++) {
 
@@ -566,6 +568,10 @@ export function fuzzyScore(pattern: string, patternLow: string, patternStart: nu
 
 			const score = _doScore(pattern, patternLow, patternPos, patternStart, word, wordLow, wordPos);
 
+			if (patternPos === patternStart && score > 1) {
+				hasStrongFirstMatch = true;
+			}
+
 			_scores[row][column] = score;
 
 			const diag = _table[row - 1][column - 1] + (score > 1 ? 1 : score);
@@ -604,6 +610,10 @@ export function fuzzyScore(pattern: string, patternLow: string, patternStart: nu
 		printTables(pattern, patternStart, word, wordStart);
 	}
 
+	if (!hasStrongFirstMatch && !firstMatchCanBeWeak) {
+		return undefined;
+	}
+
 	_matchesCount = 0;
 	_topScore = -100;
 	_wordStart = wordStart;

src/vs/base/test/common/filters.test.ts

@@ -343,6 +343,36 @@ suite('Filters', () => {
 		);
 	});
 
+	test('Freeze when fjfj -> jfjf, https://github.com/microsoft/vscode/issues/91807', function () {
+		assertMatches(
+			'jfjfj',
+			'fjfjfjfjfjfjfjfjfjfjfj',
+			undefined, fuzzyScore
+		);
+		assertMatches(
+			'jfjfjfjfjfjfjfjfjfj',
+			'fjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfj',
+			undefined, fuzzyScore
+		);
+		assertMatches(
+			'jfjfjfjfjfjfjfjfjfjjfjfjfjfjfjfjfjfjfjjfjfjfjfjfjfjfjfjfjjfjfjfjfjfjfjfjfjfjjfjfjfjfjfjfjfjfjfjjfjfjfjfjfjfjfjfjfj',
+			'fjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfj',
+			undefined, fuzzyScore
+		);
+		assertMatches(
+			'jfjfjfjfjfjfjfjfjfj',
+			'fJfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfj',
+			'f^J^f^j^f^j^f^j^f^j^f^j^f^j^f^j^f^j^f^jfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfj', // strong match
+			fuzzyScore
+		);
+		assertMatches(
+			'jfjfjfjfjfjfjfjfjfj',
+			'fjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfj',
+			'f^j^f^j^f^j^f^j^f^j^f^j^f^j^f^j^f^j^f^jfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfjfj', // any match
+			fuzzyScore, { firstMatchCanBeWeak: true }
+		);
+	});
+
 	test('fuzzyScore, issue #26423', function () {
 
 		assertMatches('baba', 'abababab', undefined, fuzzyScore);