Codeigniter + compiled language

[eluser]Byrro[/eluser]
Hello,

I´m starting a web application that will require lots of mathematical calculations. It´s gonna be very very slow in PHP so I believe it´s necessary to use a compiled language.

Is it efficient to use Codeigniter as a front-end and something like C as back-end (for the maths)?

My background is only PHP. What compiled language do you suggest (shortest learning-curve)? How does it work? I´ve been searching this on google and haven´t found good directions, if you could share experiences, point me some website or especific forum...

Thanks a lot!