This game runs surprisingly awesome...
My Specs (See sig) 60fps/70fps at 1650X1080 everything maximum.
Explosions/Fire make no difference to the fps at all.
Btw, The map editor is SUPERB. It is truly awesome, it's so easy to use yet lets you have lots and lots of customization.
When you say the game runs awesome do you mean the editor or did you get the game itself to run?