Issue Description
Your project contains lots of necessary objects and your finding your 3D is really starting to lag
Solution
Use the MVOs, Objects, and Lamps detail level settings defined here under the miscellaneous settings
Object and Lamp Detail Level
Set the Detail Level for 3D projections So you can work in a view that performs faster.
Full
Simplified
Schematic
Objects and Lamps use the detail level settings defined here by default (By MVO). For a specific object/lamp, if the control is available, you can override its detail level in Element Settings (use the 2D or 3D Representation controls)