Input lag of 1 frame randomly?

[eyes of darkness]

I make TASes of SSBM which are essentially frame by frame runs of things like break the targets or event matches for optimal time. Recently I noticed that the input is becoming "late" by a frame, as in I'll input a move, and the game won't register that I did anything until the next frame, which people normally wouldn't notice, but is very inconvenient for me. I had this problem before, which I thought I fixed by disabling Dual Core, but it's back again and I was hoping someone had an idea why this happens and how to solve it. Thanks.

[eyes of darkness]

Bump.