Strange Lag/FPS drops in certain biomes?

[jonman135]

For some reason whenever i enter certain biomes such as the coniferous forest or the swamp biomes (From biomes o' plenty) i encounter a huge drops in fps. i am not sure why. Also, i am restricted to normal render distance and only  fast graphics. This is only when i play attack of the b-team however, when i play other mod packs such as monster from the ftb launcher i am able to play on far render dist. and fancy graphics and i experience no lag or fps drops. I have a hard time understanding this because attack of the b-team has about 113 mods (as of right now) and monster has over 180 i believe. I really want to get into attack of the b-team but when i only get a max of anywhere from 1 to 10 fps it is to unbareable to even try. I've tested in both multiplayer and single player and i experience the same issues. Please give me an answer if you can help me out in anyway, thank you for your time.

 

P.S.

some of my computer specs:

 

GeForce GTX 670
Intel® Core™ i7-3820 CPU @ 3.60GHz
16.00 GB RAM
Microsoft Windows 7 Professional