While working with relatively large matrices and vectors of polynomial expressions I've noticed that some operations take quite a lot of time to finish, which is to be expected. Yet, it would be great if Maxima could perform certain tasks in parallel in order not only to speed up things but also to fully take advantage of today's hardware.
Thanks for your interest in Maxima. Exploiting parallelism in algebraic operations is impossible, given Maxima's architecture. It is a worthy goal, but impossible without rewriting Maxima. Therefore I'm closing this item.