Amdahl’s Law is one of the most important pitfalls in computer science especially when it comes to discussion of computer performance. It states that the overall performance improvement possible with a given improvement is limited by the amount the improvement feature is used. It is a quantitative version of the law of diminishing returns which is given by the following equation:
Overall Improvement = (Improvement in a certain area/Factor of improvement in that area) + Original performance in the remaining area
The following video by Prof. Rutherford further explains the concept:
Conclusion: As explained in the video, making an improvement by a factor of 2 to a certain area responsible for a performance only increases the overall performance by 1.34 (Law of diminishing return).