https://en.wikipedia.org/wiki/Amdahl's_law

For anyone who hadn't heard this before, like me. <3

In computer architecture, Amdahl's law (or Amdahl's argument[1]) is a formula limiting the speedup of a task as resources are added to the system executing that task.

The law can be stated as[disputed – discuss]:

    the overall performance improvement gained by optimizing a single part of a system is limited by the fraction of time that the improved part is actually used.[2]

Amdahl's law is often used in parallel computing to predict the theoretical speedup when using multiple processors.