Memory optimization in unity

I’m making a VR application in unity3d which I optimized as much as I can. I’ve made 2 scenes. After playing same scene again and again the application starts to lag on VR devices. And works smoothly if application is restarted and game is continued from last scene . How can I clear previously loaded scene in Unity3d or overcome the problem I mentioned above ?

Normally, when loading a scene, everything in the previous scene is deleted. If the game lags when loading a new scene, you might want to use Resources.UnloadUnusedAssets.

And as DanielAllison said, please make sure you’re loading the scene properly.