I've got almost 100 projects in my solution, and it usually takes around 5 minutes to build all the projects. So, normally I'll open the configuration manager, and deselect the projects that I want to exclude from the build, and will build the solution. Selecting or deselecting each and every project is painful, please let me know if there is a way to select or deselect all the projects.
Set up your solution using Solution Folders. You can then unload all the projects in a folder by right-clicking on it and selecting Unload All Projects. Then those projects are not rebuilt and you do not need to change anything in the Configuration Manager.
we have over a hundred projects and i had the same issue
then realised you can just uncheck the first item, then press sequence:
...repeatedly. Makes it a very fast operation.