In some instances, the performance of a VPS is limited to the hardware and software specifications of the host machine. You have a finite amount of CPU and memory resources at your disposal, and you are not free to change the operating system’s global configurations. Nevertheless, there are a plethora of OS and software parameters that you can manipulate to boost your virtual private server’s performance.
Web server tweaking – You can enable features like dynamic module management, caching and limiting running processes. Remember, you VPS likely has a limited amount of RAM, and many web server processes and functions can drain a lot of that memory.
Optimize database memory usage – Database systems like MySQL can use a lot of memory, and some VPS platforms will essentially fall apart under heavy MySQL loads. A number of functions in my.cnf can help reduce memory usage, such as disabling BSD DB and InnoDB, increasing key_buffer and use of query cache.
Finally, make sure you are only running applications and services that are necessary for your VPS. Eliminate the ones you do not need, and you will free up a lot of CPU cycles and memory for the applications your server actually uses.