It won't matter for the folks at the venue... since they are mostly the wealthy men and women of the business and would most likely not show up until the main attraction.
Meanwhile, the common fans(casuals and hardcores alike) will most likely suffer a mild coma during the undercard's duration.
I have an eerie feeling that the main event will be a "snoozer" for most of the spectators as well. At this point.. the fight is more or less a novelty for the men and women of celebrity/political status.