while it may not be as clean cut as i made it out to be, it will help. for example, from my benchmarks, maya 3d literally gets a 100% if you set the CPU affinity to 1 core then change it to 2 cores.
Compared to older multicore systems, multithreading has become a lot more efficient where theres almost no overhead (at least in terms off what can be detected in most benchmarks)
with people, multithreading is bad for small tasks because the stereotypical view of human multithreading is government
where you send in a form, 1 peoson reviews part of it, then sends it off to another worker where it sits on their desk until they are finished eating lunch and socializing, then it is skimmed over, mistakes are made and it is passed on to a commitie where it is reviewed and denied because there were mistakes, then you are called in to correct the mistake that the worker made, then resubmit the form for the entire process to happen again in the hopes that the worker will not make a mistake this time, when in reality all that needs to be done is for a worker to give the ok to forward another document to another government office where in which the college you are attending has access to, so that you may get financial aid.
anyway, with a CPU, small tasks can be multithreaded with little to no overhead.
Keep in mind that a GPU is already massively multithreaded, and a simple task such as running a really old game and it gets like 10,000 FPS when vertical sync is disabled