Why framerate of Unity's example SewerProject's scenes higher than an empty new project?

Hi, I'm new to Unity and still just making tests, yet Unity totally rocks. However I am facing what's for me a rendering mystery in Unity's editor; I will be thankful if you can enlight me on the matter:

I started a very basic test project: an orthographic cam and an inclined quad lit by a fixed parallel light and a point light that moves above the quad. I have also downloaded SewerProject from Unity's resources and I have noticed that, surprisingly, this project runs at much higher framerate (in the editor) than when I create a new project: 1000-2000 against 100-200 for a new empty project! However I could not find any difference in player/rendering settings...

Whatever, I copied my test project's assets into SewerProject's. I removed all original SewerProject's assets so both my original TESTProject and the project made from SewerProject are identical. => My project "made from SewerProject"'s framerate is as high as the original SewerProject, i.e. 1000-2000 fps, whereas my original TESTProject's framerate is ten times slower.

Do you know why SewerProject's scene, and any scenes put in it, runs at a much higher framerate in the editor than scenes from fresh projects, using default settings? (Does it happen just on my computer? BTW: Unity 3.5.5, Windows Vista pro 64 bits, gfx: NVidia GeForce 9600M GT, build setting for PC/Mac Standalone - but it's the same with Android)

If you want to check both projects and scenes: http://ge.tt/5FMpasM/v/0?c

Edit: I was also facing another rendering mystery but it disappeared as suddenly as it went so I guess it's just me not knowing all Unity's settings. ^^

Many thanks if you can light me up!