Compilation vs execution time and performance of compilation

It is my understanding that most modern javasscript engines use some sort of (JIT-)compilation.

I was wondering what a typical compilation vs execution ratio for a web application is and coudn开发者_开发问答't find any references.

Of course there will be large differences depending on the type of web application (benchmark test, graphics heavy, google maps/mail type of web apps, etc.) but still, does anyone know of any statistics published by the different engine creators? Be it statistics measured on some of the JS benchmark tests or even real world collected data.

How does JS compilation performance compare to say C, C++, other compiled languages?