That sounds like the same problem posted on Steam. Try this:
Go to steam/steam apps/common/rf2/user data/player/player.JSON click on that to open.scroll down to Graphic Options scroll down to the line Heat FX Fade Speed if that is on 30 change to 0 exit and save . make sure rf2 is CLOSED when you do this as it may not work if RF2 is open
don't work ... any idea to solve it ??