The areas that I've focused in the past for achieving the desired levels for the key architecture quality attribute for software solutions, performance,  include fine tuning of database queries and introduction of caching at various layers. While there are multiple approaches available for caching frequently used data to avoid expensive network round trips and high payloads for better performance, the project code named 'Velocity' deserves special attention.

"Microsoft project code named “Velocity” provides a highly scalable in-memory application cache for all kinds of data. By using cache, you can significantly improve application performance by avoiding unnecessary calls to the data source. Distributed cache enables your application to match increasing demand with increasing throughput by using a cache cluster that automatically manages the complexities of load balancing. "

Blogs on Velocity