4.8 project opened in 4.11 frame rate dropped?

Development Architectural and Design Visualization
1

I opened a simple one room apartment scene that I created in 4.8 and it completely bogged down in 4.11 while previewing the matinee sequence. Can anyone tell me why?

Thanks.

2

You might have to rebuild lighting

3

Nope no go, the level is a disaster! Man, this software is by far the coolest and worst I have ever used all at the same time.
All the meshes look bad, no shadows, over exposed etc. etc.