Hello CristiOne,
There is so much to be done to get everything performing at maximum optimization although there is no way to further optimize your current server.
It depends a lot on your platform, software and hardware. A Google search will give you numerous options for there is so much to fit on one post here. Configurations that work with one server would be entirely useless with another.
You require proper knowledge to fine tune your configuration files to obtain maximum potential from your hardware.
Part of your due diligence on a Web Host before engaging their VPS or Dedicated Server service is making certain they have a highly trained system administrator packing years of knowledge and experience in platform management. Also, you could ensure the Server is managed via the Hosting Provider.
Easiest way is you buy extra RAM for your VPS, I mean you need to increase RAM for your VPS to accommodate more user online online all the time, When you get overload with RAM mean your website traffic increase and it's success for you, don't worry about that. Just solve problem on RAM and you will have more successes with your website.
Good luck!
