A Computational Complexity developer focuses on understanding and analyzing the efficiency of algorithms. They study the time and space requirements of algorithms in terms of their input size, typically using Big O notation. Their work involves devising efficient algorithms that perform tasks with minimum computational resources. They also classify problems based on how difficult they are to solve, categorizing them into complexity classes like P, NP, and NP-complete. They might also work on proving theoretical limitations of certain algorithms. Their research has significant implications in fields such as cryptography, artificial intelligence, and data analysis.