I'll look at your system, see if I can solve the mystery...
You see, you have the first event move to the center, then right, then right again.
At the SAME TIME you have the other one move right, just 1 frame after, which of course, the first flame is there, since it takes a few frames to move over.
I added a wait until move completion thing, and it works.
Nothing happens to the players movement, but it does take longer to start the first opacity change.
As for the other problem, I think it's fine, it doesn't change much gameplay, but it does remove some FPS on older computers.