I wouldn't worry about it. You can always use Disk Cleanup (just type it from the Start screen to find). You can also view how much space your apps are using by going to: Settings > Change PC settings > General > Available Storage > View app sizes
Windows RT, windows 8 metro in general, handles this very well. It may seem instantaneous but likely some work is being done in the background. I've been very impressed how this first gen product delivers.