How to reproduce:
1. Open attached Unity project
2. Load "test" scene
3. Select event_catattacs in the Hierarchy window
4. Open Animation window
5. Select all key frames
6. Try to drag selected key frames

Expected result: Key frames move while dragging.
Actual result: Editor freezes for a few seconds (about 30).

Reproduced with: 2018.2.0b4, 2018.1.0f2, 2017.4.3f1, 2017.2.3f1, 2017.1.3p4.