g3gg0 did some changes on the EDMAC side for mlv_rec. If the improvement is only on mlv_rec and not on raw_rec, it's from his changes.
Back then I ran my tests without recording, but with grayscale preview on (this way I was getting a lot of pink frames).
May be worth checking both methods combined (5D3/60D users, please report, because you have both fixes applied).