Building the solution depends on a lot of factors, for instance your computers hardware. Previous machines I had a standard hard drive in and my new ones I've purchased SSDs which have reduced the build time by over 50% if not more. The Kentico project is a very large project with many inter-dependencies. What the build is doing is checking all those dependencies with the 170+ different custom Kentico DLLs and other class libraries. It takes a while but that's just the nature of the beast. There are other ways to reduce that time but it won't ever cut it down to seconds or even a minute.