I find that if you want to serve large websites more oft then not Frameworks simply hold TOO much of what you don't need, TOO little of what you do need, and everything in between is nearly unchangeable without breaking a dependent library. So my advice is to build your own system of doing things, not necessarily a framework but simply a way of going about things which you can easily understand and document.

On a side note, if you are HEAVILY acquainted with a framework, that you may use that framework so long as your mastery of it is such that you can alter the internals of said framework comfortably.