I found a workaround that fixed my lag issues.
All of my RGB Stuff starts at channel 501. Since I don't use channels 400-450, I selected those 50 channels for the entire sequence and had vixen do a random effect on those 50 channels for the entire song. I re-converted it to XSEQ format and bam, the problem is fixed.
I had sequences starting in the 2nd and 3rd universes. Having information in the first universe helps for some reason.
That's what I've found works for me.
I prefer xlights for the scheduler alone. It also shrinks down larger vixen files to help the show computer run smoother - which in my case is a super old computer.
Steve