I'm not sure it is better, unless you can do autocorrelation in hardware without using an fft. This option is unavailable on standard PCs. If done in software

I'm not sure it is better, unless you can do autocorrelation in hardware without using an fft. This option is unavailable on standard PCs. If done in software then a simple implementation of autocorrelation is O(n^2). An efficient implemementation is O(n.log(n)) (it uses two ffts).