Christof Paar & Jan Pelzl
The affine step “destroys” the algebraic structure of the Galois field, which in turn is needed to prevent attacks that would exploit the finite field inversion. (Paar & Pelzl 2010, 103)
Many block and stream ciphers can encrypt about one hundred to one thousand times faster than public-key algorithms. (Paar & Pelzl 2010, 154)
In practice, RSA is often used together with a symmetric cipher such as AES, where the symmetric cipher does the actual bulk data encryption. (Paar & Pelzl 2010, 174)