Visual Studio, by default, displays a splash screen at startup. The splash screen displays branding information for Visual Studio and also includes information (if supplied) for all packages installed.
This information can take time to display and many developers do not wish to see this each time Visual Studio is started, preferring instead to get right to the job at hand.
The display of the splash screen can be turned off by passing the /nosplash parameter to devenv.exe. The shortcut for Visual Studio can be modified so this happens automatically.
Some developers have told me they see up to a 10 second difference. The difference on my machine seems like a second or two at most but your mileage will vary based on the speed of your machine. At a minimum you can skip it if you are not interested in seeing it any longer.