.Net has become one of the most popular, and perhaps the most dominant, development frameworks used to implement various types of applications. Analogously to those above, .Net has taken on the responsibility of managing large amounts of data. Processing large amounts of data usually lead to slowdowns and require detailed analysis and optimization. In other words, creating more efficient programming code than usual is necessary. In this lecture, the participants will be introduced to Visual Studio tools that identify performance-problematic parts of code, a set of data types recommended for improving work with large data sets, and a library for performance testing - Benchmark with comparative analysis.