Project Takes Over An Hour To Load Up: What Exactly Is Going On At 94% ?

Hey guys, ive been having such long load up times with my open world project ive been making for a few months now. it really slows down at 93-95% project load. it takes any where from a half hour to an hour to load, i never used to experience such long load times.
what exactly is happening at 93-95% load times? is it loading content browser? if so does that mean i have either too much or something very large to load in the content folder i should look into deleting?

please let me know what i could possibly do to decrease load time! thanks so much.