Unity 5 canvas animation laggs, why?

I'm trying to implement a feature like the motion picture credits, it works just fine except for the fact that it doesn't run smoothly. There are only 13 gameobjects involved in the animation, 2 of them are images (one is: 128x88 pixels and the other: 64x64 pixels) the rest are texts with outline and shadow.

In the profiler, I can see the frame rate drops below 15FPS for about 100 frames, then it speeds up to above 60FPS for another 100 frames or so and the cycle repeats itself over and over again. In the overview panel it seems like Canvas.SendWillRenderCanvases() is responsable for most of the lagging. But also Animator.Update/Dirty Scene Objects/Pyisics2D.ColliderTransform.Changed() has some impact, what puzzels me is that none of these gameobjects has a collider attached to them.

Any advice will be appreciated.