This applies to a solution that has enable nuget package restore option checked. If you just close visual studio, and then reload the solution, visual studio with exec nuget install package for every project/every package in that project. This causes 2 minute + load times. The workaround for this is to close all open window tabs in the solution then File= > close solution. It will then load with normal times until you close again without following the workaround.
Visual Studio/Team Foundation Server/.NET Framework Tooling Version
Steps to reproduce
Operating System Language