Linear-Phase FIR filters I understand the four different type os FIR filters however i don´t understand why do linear-phase FIR filters offer opportunities for efficient realization.
Linear phase FIR filters should have some sort of symmetry (even or odd)  in their coefficients which will reduce the number of independent multiplications by about two yielding an efficient realization compared to a nonsymmetric FIR filter of the same length.

However, linear phase FIR filters are important not because of their computational efficiency but for their linear phase property.