If i play this game i play for a long period of time. I can be playing for 6 hours and will have to force close the game at least 4-5 times because of the white screen of death and it takes like 10 mins each time to start it.. The game runs perfectly fine 130-160fps constant. Sometimes it will pause and catch up with itself but there has to be a way to make this pack more stable as this is rediculous now. Its not my pc as i have a friends pc that has a i7 in it (mines a i5 6600k) and he gets the same issue. any reason for this?

This is normal. Minecraft is not completely optimized, so it has memory leaks. These leaks pile up over time and make things take too much ram to run. You can try running through these changes to help optimize as much as possible, but you wont be able to fully get rid of the leaks. https://www.reddit.com/r/allthemods/comments/968r4k/how_to_fix_modpack_wont_load_fps