Benched using single-threaded full decode on an Ampere Altra.

Bpp Before  After  Speedup
8   73,3s   65,2s  1.124x
10  114,2s  104,0s 1.098x
12  125,8s  115,7s 1.087x
Signed-off-by: J. Dekker <jdek@itanimul.li>