See case 786702 for minimal repro project.

Instructions:

On Version 5.4.0b10 (d5987c96f84a)
Tue, 08 Mar 2016 20:19:21 GMT
Branch: 5.4/staging

(reported on 5.4.0b9) as well

1) Download project
2) Set up HTC Vive w/ steamVR, etc.
3) Open the only scene in the project
4) Press play
5) Stand up (either hold the headset or put it on)
6) walk around the room scale scene, keeping an eye on the lights and cubes
7) do this long enough (Always under a minute for me) and the editor will crash.