I have aplication where i can import 3D models into scene. I need to know some limits how many models there can be imported. If i import a lot of 3D models application and laptop will crash.
What does the number of models I can insert into the scene depend on? I tried this performance memory test and when is buffer full it will crash what is the buffer, it is relevant? My models are not optimalized so they are big. But depend limit on RAM or cache or GPU?
It depends on a lot of stuff 
number of vertices, types of shaders used, memory available, etc etc I recommend taking a look at Optimizing Your Scene | Babylon.js Documentation (babylonjs.com) for some general performance tips.