FTB Modpack Question

[Julian123456]

I don't know why but when i play the FTB modpack i get great fps(45). but when i switch over to dw20 pack i get insane lag EVERY time i open my inventory.. i think its NEI. i get 35 fps without opening my inv but then it goes down to 1fps... i REALLY want to play dw20 pack but i dont know what to do.. i have installed optifine and set it on the lowest settings possible, and still it doesnt work... i tried removing the recipes from nei so that there was only 1 page of them and still evry time i opened my inv i would go down to 1fps. and yes i do the "O" key to disable it, but even disabled i still go down to 1fps. its like a HUGE lag spike every time...