On my test. benchmark testing, it is about 20% faster.
But when I use the real program, such as phpBB 3. It is only 5% improvement on loading.
http://www.yinfor.com/blog/archives/2013/09/php_55_vs_php_54_vs_php_53_-_p.html This is the test of PHP5.5 vs PHP5.4 vs PHP5.3