[php-src] Issue #7847: stripos has very bad performance

Issue: https://github.com/php/php-src/issues/7847 Author: woho ### Description stripos is slow because both input strings are always lowercased completely. This also entails unnecessary memory consumption. preg_match with case-insensitive flag is a much faster alternative. Source code: https://github.com/php/php-src/blob/9362d6f5f08bf5f86fc30cf12433e1634f746c4d/ext/standard/string.c#L1914 Test case: ```php <?php $haystack = str_repeat('A', 1e+7) . 'BBB'; $repetitions = 0; $start = microtime(true); do { strpos($haystack, 'bbb'); $repetitions += 1; } while (microtime(true) - $start < 5); $rate = round($repetitions / (microtime(true) - $start)); $rate = str_pad($rate, 8, ' ', STR_PAD_LEFT); print("strpos: $rate / second\n"); $repetitions = 0; $start = microtime(true); do { stripos($haystack, 'bbb'); $repetitions += 1; } while (microtime(true) - $start < 5); $rate = round($repetitions / (microtime(true) - $start)); $rate = str_pad($rate, 8, ' ', STR_PAD_LEFT); print("stripos: $rate / second\n"); $repetitions = 0; $start = microtime(true); do { preg_match('/bbb/i', $haystack, $match, PREG_OFFSET_CAPTURE); $repetitions += 1; } while (microtime(true) - $start < 5); $rate = round($repetitions / (microtime(true) - $start)); $rate = str_pad($rate, 8, ' ', STR_PAD_LEFT); print("preg_match: $rate / second\n"); ``` Example output: ``` strpos: 1192 / second stripos: 176 / second preg_match: 1118 / second ``` ### PHP Version PHP 8.0.14 ### Operating System _No response_