smoke doubles my render time

hi, I have a problem where im using smoke and it doubles my render time from 19 minutes to 46 minutes. is there a way to render it seperately and composite in the smoke or do something to lower the render time as I am trying to make an animation?
19 minutes:

46 minutes:

one of the reasons it takes a while is because of indirect lighting and global illumination settings i added in in addition to my regular lighting setup. I just wanna be able to render the smoke separately or do something so i can composite the smoke in so I can lower my render times.

maaaaaan every time I think I’m stumped on something and I’ll never be able to figure it out I figure it out like 30 minutes later; I just use a luminance key and set everything in the background to be black…bleh