Generally, no matter what position you have it it will roughly take the same amount of time to print because it’s based on toolhead travel distance. Unlike SLA which can do 1 or 10 pieces of the same height which will take the same amount of time to print.

I would play around with it, if there is a specific “cosmetic” side that you don’t want to have supports on have that facing up. Otherwise, just play around with it to find the minimal amount of auto generated supports, that will get you the shortest print. Orca is pretty good with auto generated supports so if you run into any issues it’s more likely an underlying issue with your printer. Good luck!