Innovations in encoder-side decisions that use the results of hash-based block matching when setting parameters are presented. For example, some of the innovations relate to ways to select motion vector precision depending on the results of hash-based block matching. Other innovations relate to ways to selectively disable sample adaptive offset filtering depending on the results of hash-based block matching. Still other innovations relate to ways to select which reference pictures to retain in a reference picture set depending on the results of hash-based block matching.