Gzip compression is a method of compressing files to make them them smaller so that it will be faster for network transfers. It is a standard practice that we must enable compression for production websites. We can enable gzip compression by adding following set of code in your .htaccess file.
XHProf is a function-level hierarchical profiler for PHP and has a simple HTML based navigational interface. The raw data collection component is implemented in C (as a PHP extension). The reporting/UI layer is all in PHP.
Memcached is an open source, distributed memory object caching system that alleviates database load to speed up dynamic Web applications. Memcached stores data according to a key. Data can be of various sizes so you can store small bits (like 1 record pulled from the database) or you can store huge chunks of data (like hundreds of records, or entire finished html pages).