This book presents efficient numerical strategies for solving singular perturbation problems, particularly focus on differential-difference equations involving small delay parameters. Singular perturbation problems in various fields of engineering and applied sciences such as fluid dynamics, elasticity, quantum mechanics, electrical networks, are known for their boundary layer behavior, which challenges conventional numerical methods. This book reviews the theoretical background and existing literature before introducing two high-accuracy techniques: a Fourth-Order Adaptive Cubic Spline Method and a Variable Mesh Scheme. These methods are rigorously analyzed for stability, convergence, accuracy and are validated through extensive numerical experimentation. The work is motivated by the limitations of classical techniques and addresses the growing demand for robust computational methods in fields such as fluid dynamics, quantum mechanics, and reaction- diffusion process.