Disagreement between Analytic Convolution and FFT Convolution

1. Why is FFT convolution faster?

Why is FFT convolution faster?

FFT convolution uses the overlap-add method together with the Fast Fourier Transform, allowing signals to be convolved by multiplying their frequency spectra. For filter kernels longer than about 64 points, FFT convolution is faster than standard convolution, while producing exactly the same result.