This setting controls how much time is added onto the load screen to do additional script processing in case the cell being loaded into needs to set itself up. Adjusting the time will adjust your visible load screen time. Adjust this setting if a cell with very complicated scripting is not getting quite set up in time by the time the player loads. This also may depend on the story manager since quests may not start until the load screen finishes if they are started up right before the player hits a load door. If the quest initial stage has a lot of scripting then it may need the extra time to run before the load screen is pulled down.