My Unity Keeps freezing; Windows 7

I am using Unity 5.01 right now and I am in the process of making a open world game. I have drawn assets in Sketchup, exported them as .dae files and then imported them into Unity. However, when I put more than 5 of them custom 3D models from sketch up into the Unity Editor, the whole program freezes up and doesnt move. I have to then force quit and start over again. When I dont place more than 5 of thesse object, the editor seems to run just fine. I know it isnt a issue with the computer capabilities because I have a i7 5930k, gtx 980 SC, and 16 GB of DRR4 ram. The project I am making is REQUIRES me to be able to use these sketch up assets. Let me know if this is a fixable issue.