Engine hangs after few minutes

Recently I installed Unreal Engine 4.13, but it is impossible to work with it on my PC. After few minutes editor becomes unresponsive and all I can do is to end process from task manager.
I installed 4.11.2. Unfortunately same effect occurs.

Maybe my spec is not enough:
8GB of ram
nvidia 960m

Your specs are more than enough, The first time you run the engine it takes time to upgrade the old project to the newer version. If that is not your issue, if you leave it hanging for a while does it unfreeze? If not, it seam like you might be having a memory leak. Also try to update your nvidia driver