Just likely your PC, when you run programs on it, they put some weight on it's RAM, games do the same with your GPU RAM. When there's insufficient space, it will start to stutter and freeze, not running properly.
Newer games tend to 'weight' more than older ones, so it will consume more RAM space, therefore you will want the video card with more VRAM.
I'd recommend, no doubt, the 4GB Version of the 1050Ti or a RX470 if you can grab one around the same price, as it's better than the 1050Ti.