Some other projects, such as Zephir, provide the capacity for PHP expansions to be developed in a top-level language and put together right into native PHP expansions. Such a method, instead of writing PHP extensions directly in C, simplifies the development of expansions and also decreases the time required for programming and screening. PHP's single-request-per-script-execution version, and the fact the Zend Engine is an interpreter, results in inefficiency; because of this, various items have been developed to help boost PHP efficiency.