"What can you do?"
Hello, I've read your project description and I understand that you're looking for someone to optimize your VPS. For this job, I'd suggest you to install this stack: nginx (which is faster and lighter than apache httpd), php-fpm 5.6 (latest, fastest), mariadb (open source and faster than mysql). When you use nginx, you also leverage the best of client caching, which is apache is worse. With PHP 5.6, it comes with zend opcache, which is less buggy and faster than APC. There're many things else to do, but I'll have to take a look for the best solution. Please take a look at my profile, as I have done many Linux optimization project before.
My name is Duc Nguyen, and I'm a Web Developer with more than 5 years experience working with PHP, MySQL, Twitter Bootstrap, etc. Also, I'm a fulltime freelancer so I can start the job right away, and right now I'm having 100% completion rate because I'm committed 100% to a single project at a time. I'm asking higher for higher price than other competitors, but I believe, this job will worth the price.
Hope to hear from you soon.
Best regards.