$datasets = [
 'a' => [new UrlScript('/projects/blog/www/'), '/projects/blog/www/index.php', '/projects/blog/www/'],
 'b' => [new UrlScript('/projects/blog/www/contact'), '/projects/blog/www/index.php', '/projects/blog/www/'],
 'c' => [new UrlScript('/projects/blog/www/index.php'), '/projects/blog/www/index.php', '/projects/blog/www/index.php'],
 'd' => [new UrlScript('/test/in'), '/test/index.php', '/test/'],
 'e' => [new UrlScript('/test//'), '/test/index.php', '/test/'],
];
$tests = [
 'old' => function ($testCount, UrlScript $url, $script, $expected) {
 for ($x = 0; $x < $testCount; $x++) {
 $path = strtolower($url->getPath()) . '/';
 $script = strtolower($script) . '/';
 $max = min(strlen($path), strlen($script));
 for ($i = 0; $i < $max; $i++) {
 if ($path[$i] !== $script[$i]) {
 break;
 } elseif ($path[$i] === '/') {
 $url->setScriptPath(substr($url->getPath(), 0, $i + 1));
 }
 }
 }
 Assert::same($expected, $url->scriptPath);
 },
 'new1' => function ($testCount, UrlScript $url, $script, $expected) {
 for ($x = 0; $x < $testCount; $x++) {
 $path = $url->getPath();
 $min = min(strlen($path), strlen($script));
 for ($i = 0, $j = 0; $i < $min; $i++) {
 if ($path[$i] !== $script[$i] && strcasecmp($path[$i], $script[$i])) {
 break;
 } elseif ($path[$i] === '/') {
 $j = $i;
 }
 }
 $url->setScriptPath($i === $min && strlen($path) === strlen($script) ? $path : substr($path, 0, $j + 1));
 }
 Assert::same($expected, $url->scriptPath);
 },
 'new2' => function ($testCount, UrlScript $url, $script, $expected) {
 for ($x = 0; $x < $testCount; $x++) {
 $path = $url->getPath();
 $max = min(strlen($path), strlen($script));
 for ($i = 0; $i < $max; $i++) {
 if ($path[$i] !== $script[$i] && strcasecmp($path[$i], $script[$i])) {
 break;
 }
 }
 $url->setScriptPath($i === $max && strlen($path) === strlen($script)
 ? $path
 : substr($path, 0, strrpos($path, '/', $i - $max - 1) + 1)
 );
 }
 Assert::same($expected, $url->scriptPath);
 },
 'new3' => function ($testCount, UrlScript $url, $script, $expected) {
 for ($x = 0; $x < $testCount; $x++) {
 $path = $url->getPath();
 $max = min(strlen($path), strlen($script));
 for ($i = 0; $i < $max && ($path[$i] === $script[$i] || !strcasecmp($path[$i], $script[$i])); $i++);
 $url->setScriptPath($i === $max && strlen($path) === strlen($script)
 ? $path
 : substr($path, 0, strrpos($path, '/', $i - $max - 1) + 1)
 );
 }
 Assert::same($expected, $url->scriptPath);
 },
];
$testCount = 10000;
$padLength = max(array_map('strlen', array_keys($datasets))) + 3;
foreach ($tests as $testName => $testCallback) {
 printf("Test %s:\n", $testName);
 foreach ($datasets as $datasetName => $dataset) {
 $time = -microtime(TRUE);
 $testCallback($testCount, ...$dataset);
 $time += microtime(TRUE);
 printf(" %s%5.0f ms\n", str_pad($datasetName, $padLength), $time * 1e3);
 }
 printf("\n");
}

Test old:
 a 1045 ms
 b 1049 ms
 c 1075 ms
 d 1002 ms
 e 1007 ms
Test new1:
 a 56 ms
 b 58 ms
 c 75 ms
 d 31 ms
 e 28 ms
Test new2:
 a 44 ms
 b 46 ms
 c 54 ms
 d 27 ms
 e 25 ms
Test new3:
 a 46 ms
 b 46 ms
 c 54 ms
 d 27 ms
 e 26 ms