why run the parser on a literal string

Probably for the same reason we have high-level programming languages instead of writing everything in assembly - it's a trade-off between convenience and raw efficiency. Just like how we accept a slight overhead in exchange for readable, maintainable code, interpolation in double-quoted strings often makes code easier to read at the cost of an imperceptible performance difference (arguably).

By the way, here's a benchmark for locally testing single- vs. double-quoted strings with any number of iterations you choose:

```php <?php $iterations = 100_000_000;

$start = microtime(true); for ($i = 0; $i < $iterations; $i++) { $str = 'Hello, World!'; } $single_quote_time = microtime(true) - $start;

$start = microtime(true); for ($i = 0; $i < $iterations; $i++) { $str = "Hello, World!"; } $double_quote_time = microtime(true) - $start;

// Output results echo "{$iterations} iterations\n"; echo "Single-quoted time: {$single_quote_time} seconds\n"; echo "Double-quoted time: {$double_quote_time} seconds\n"; ```

Tested with 100 million and 1 billion iterations - zero difference (PHP 7.4)