Steps to reproduce:
1. Open attached project
2. In the project window select Animations/Samples/AnotherCameraTest_Movement
3. In the Animation window click on curves and zoom out as much as possible
4. Observe the editor freeze

Expected result: animation curves should not cause a freeze in the editor

Reproduced in: 2017.2.0a3, 2017.1.0b9, 5.6.1p3, 5.5.4f1, 5.5.0b1
Not reproduced in: 5.4.5p3
Regression since: 5.5.0b1