If you are using the mouse pointer in your level you will gain a lot of fps by assigning "my.untouchable = on" in the action of the entities that do not have to be recognized by the mouse. It makes those entities "invisible" to the mouse. Why does this work? Because all entities in the field of view of the camera are constantly being monitored if they are touched by the mouse arrow. I found that the jerks you get when you rotate and new entities (even high poly with hi res textures) come into view and near the mouse pointer completely disappear when their untouchable is turned on. Untouchable is turned off by default for all your intities by the engine.

For entities that have not been assigned an action it might be worthwhile to give them one with just the line:

my.untouchable = on;

Just another option to consider and check for.

Cheers