Im making quite big maps and by the time im getting to the end of my map the compile times are bordering 2 hours! But once compiled the maps run fine, no frame skips. But it does get frustrating when all your doing each time you compile is tweaking small things like sound and lighting. The thing that takes the most time is HLVIS, the rest takes about 10 minutes whilst that takes up more than an hour and a half.
So what i did was i compiled without VIS running. I thought it did something amazing thats why it took so long, but i ran may map without VIS and it didnt look any different than if if i had run VIS. Obviously when i do my final compile i'll use VIs, but i was just wondering what VIS actually does?