Help! Mipmap generation problems

[Th3D4rc]

I made a small modpack to host on my pc and play with friends, cuz big ones eat too much CPU to be playable. Anyway when made a louncher for it using MultiMC the mipmap generation, texture loading has me stuck. It is taking forever about 14/min get generated and its using 90% of my CPU. It has never been so slow with much bigger modpacks. Every other part is verry fast. What is causing this and any way to make it faster and use less CPU?
PC specs:  CPU - Intel Core i7-6700K 4Ghz
RAM - 16Gb
GPU - Nvidia 1070
I use about 40 mods: http://prntscr.com/eweuq4
 

[Th3D4rc]

+Info
After reaches ~3500/6500 craches.
Crash repport: https://pastebin.com/ZaLg6XRR
Whats wrong?