The idea of single page application is that you never leave first loaded page. This means it's impossible only with php. All other data is loaded by ajax and changes the contents of current page. It speeds up your site only in case when you can preload next page while showing the first one. But if your next part of data depends on input from the first one it cannot be faster anyway. But with single page you can preload all other files pictures, fonts, css, js etc. And after input you should not loose time for that stuff, but only for response.