Endermage93

I didn't know you could make the sky look that pretty... gives a wonderful modded Skyrim feel to it

can you use opis to track the problem? wich chunk is consuming all the resources
there is a problem with ender io and other mod that spawn like one millon enderman in the nether

i didnt installed the pack but your problem are entitys (mobs)
Install mobcontrol or a mod to control the spawning of mobs.
And install fastcraft, also you have to enable fasth math, smooth world and maybe other things and disable other with optifine
There is no reason to have less than 50 fps with any modpack in a normal pc