It would depend upon the work. If the work is embarrassingly parallel, then 25% more. (5/4 = 1.25, of course) If there is too much work for four people to fun

It would depend upon the work. If the work is embarrassingly parallel, then 25% more. (5/4 = 1.25, of course) If there is too much work for four people to function effectively, perhaps more than 25%. If the work requires a lot of inter-process communication, perhaps less than 25%.