Modelling burning area

I'm have burning area on plane (marked with red quads in screenshot). And I need to show fire on this area. By design, it's not necessarily to show fire on all red dots, I may show fire only on burning area borders (marked with yellow dots on screenshot).

Now, I can't figure out, how to implement this without performance issues. If I create particle emitter for every border dot, it will be numerous particle emitters, and will lead to low FPS.

How I may implement this performance effective?