@Wiggenstein Oh, I get it now. Nope, I'm not familiar with a forced slow down option on OPL or Neutrino, and it sounds esoteric not gonna lie, not sure if it's possible.
interlaced signal has to be deinterlaced
Even if outputting a 480p signal? Sorry if my reading comprehension is fucking me up here, I get that you're trying to output 1080i, but if the lag is bad then maybe a 480p image looks good enough? You'd still have the speedup problem though.