Computer freeze completely when building lighting/ or placing models in the level

Hello people,

since updating my UE4 to version 17, I’ve noticed that a massive model of 1000 pieces would freeze not only the engine but the whole computer indeed when I try to place them in the editor, the issue I’m looking at is that this massive model should freeze the program itself (UE4) but not the windows itself, it becomes freezed to the level that I can’t open the task manager nor lock the computer nor do anything at all literally, I often power off the computer using the power button when this happen.

note that my computer is pretty powerful gaming PC with gtx 980 and core I7 6700K and I use windows 8.1, please investigate the issue, all I want is to let the engine freeze by itself if it wants to, but to not freeze the windows itself so I can kill/re-initialize the program instead of killing the whole computer!!