Is matlab fft faster for real input?
Matlab, like most computational packages, implement a pretty neat set of fast Fourier transform algorithms referred to as FFTW: fastest Fourier transform in the west. You can find more out about it here.

FFTW actually runs a preflight on your machine when it is first installed. At that time, it runs a bunch of test computations to figure out which prime factorization would be fastest given your processor speeds and cache sizes. Then, it uses a symbolic program to generate a bunch of FFT algorithms specific to your machine for a whole bunch of cases, like real valued, symmetric, etc. So, it's hard to say exactly what's going on under the hood except that if there's an efficiency to be had, FFTW will take advantage.