Reality Factory

In my game I got a lot of small brushes in the leves.They are just details and slow the game.For example I got a room with lights,but the lights are brushes with a light texture.I want to ask If making theese brushes empty will speed up the game,I've already made them detailed,but I need more speed.What do you think guys?
EDIT: also I marked the unseen faces of the brushes as Sky

Why not make the lights actors instead of brushes? That will speed up the level a bit.

Well..I was thinking about that,but If I make the lights actors it will be the same,right?,because for each light I'll have to make an actor and if there are too many actors the game get's slow.I was thinking also of making all the lights an actor,but I'm not sure if this is a good idea so I decided to stay with brushes.

That is what static meshes are for. Static meshes take the same actor and render it in different places. Actors are rendered more efficiently than world geometry. Try it...you will notice a difference.

Thanks,I will!