is it good to use php+mysql for a large web site data base handling?

I am bit new to web development and I am a self-learner. I am developing a web site which is intended to be linked to a large data base where user inputs are stored and users can interact with data. At the moment I am using mySQL+PHP for handling the data base. For example I use PHP for pagination of data and displaying them. So, my question is if I use PHP, will it slow down the web site when the web site is accessed by many users and start fetching data from it? if so do I need to use javaScript to do the things like for example pagination? Please give me some advice and all your advices/comments/inputs are highly appreciated.