Title.
They can, yes. They're things your GPU has to render.
If there is too many.Also you should rather re-type the title than just say "title"
If I have 1500 bricks, and 300 of them are emitters, is it normal for it to lag?
But then it's redundant.Depends on if it's clustered together or spread out, also which emitters.
Fire emitters and crap like that. (Clustered)
It may.
Should I remove the emitters? Would it remove lag?
More than likely.