Parallel slowdown

https://en.wikipedia.org/wiki/Parallel_slowdown

Important concept for developers when they go full throttle on multi-threading. Too much context switching by the manager/master/coordinator becomes expensive as the parallel threads increase. Simple analogy would be to visualize a teacher teaching 20 students. If the student count is increased to 100 then we have a chaos in making as the teacher would not be able to give enough attention to the children.