Position: Разработчик PHP
Category: PHP
English level: upper
Years of experience: 11

In each project I worked in last 6 years - I improved overall performance in dozens times.  For some edge cases  improvement was in hundreds times.
In my current project, I rewrote over 10% of existing codebase in almost 3 years. Codebase is really huge and legacy here.
Primary: PHP, MySQL, Postgres, Linux, JavaScript, CSS, HTML.
Secondary: Zend expressive, CakePHP, JQuery, Twitter Bootstrap, XML, Java (Selenium).