Hexxit has major FPS lag spikes on brand new comp.

[fish123]

So recently I have downloaded the Technic platform and started playing hexxit but i can only play about 2 mins of it before my fps drops below 6-3 when i usually run 100-130 FPS with normal minecraft. I can run Skyrim, WoW, and GTA 4 on max settings. no problem. Also when i join a multiplayer server, there are some servers that have this lag spike and some that rarely don't but the server that doesnt have this problem is always down. Is there any way to fix this or is this happening to everyone? I'm getting kinda tired of closing out of minecraft and reopening it every 2 mins.