Advice needed for making a pre defined course runner game

Hello,

I am making a 3D runner style game but with a set course and set scenery. I have been creating the scenery my self and have a specific story to tell at certain checkpoints of the game. I don't want to make it procedurally. It's now time to put it all together!

My question is what is the best way to do this without impacting too much on the performance. I want the experience to be seamless. There shouldn't be any loading points.

Should I split the level up into scenes? Should I just chuck in all assets and models into one scene and hope for the best?!

I understand that I can impact what is being rendered by setting draw distances of the camera etc which should help improve performance. Are there any other methods that I should use to help with the performance?

Thanks